How It All Went - the Denouement

© ITV

During the course of nearly one year, I’ve traced the chronology of one of my favourite television series – Agatha Christie’s Poirot. Through the posts on this blog, I’ve tried to present my findings. In general, I’m surprised to find that things fitted neatly together to such a great extent. Of course, I have had to take some radical measures and set quite a few episodes earlier or later than intended, as I cannot bring myself to agree with the writers on all of them, but all in all, this project has made it evident that there really is some sort of order in the chaos – even if it wasn’t intended.

1936 – Brian Eastman’s and Clive Exton’s decision

A short while ago, I discovered an interview with the original Poirot producer, Brian Eastman, on the chronology of the series. In Agatha Christie’s Poirot: A Celebration of the Great Detective (1995) by Peter Haining, Eastman quite clearly states that it was a conscious decision to place all the stories in 1936, just as I’ve seen him state in the documentary Super Sleuths (2006) on ITV. I’ll reprint some extracts from this interview here:

“(…) to me there was something about all her [Agatha Christie’s] writing which felt pre-war (…) I felt it was important to start the series in a pre-war setting. We were also helped by the fact that many of the short stories fitted very neatly into that time frame” (p. 13).

“(…) when we were deciding on a date for Poirot we looked at all the aspects of the Thirties (…) and came to the conclusion that 1936 would be a very good year!” (p. 14).

In the same interview, script writer Clive Exton explains that the production team thought 1936 fitted very well with Poirot’s character:

“(…) In a way the mid- to late- Thirties were an incredibly flourishing and futuristic period – and Poirot was a man who was very interested in such things [modern inventions] (…)” (p. 14).

Brian Eastman adds that they did not set all episodes in 1936:

“’we do allow ourselves a little bit of license’ (…) ‘sometimes we take an event from 1935 and sometimes from 1937 – but pretty much within a twelve- to fifteen-month period (…)” (p. 15).

Interestingly, the attitude of both David Suchet and the current production team must be different from Eastman’s and Suchet’s attitudes in 1995 towards the placement of stories, as is seen in this quote from Haining's book:

“(…) eventually we shall come to books that cannot be set pre-war. Those, that is, which have integral parts that can only occur because of post-war activities. So we have been facing up to the fact that we shall have to see him go through the Second World War and then into the Fifties and Sixties. In fact, David is already thinking of how he will allow himself to age bit by bit (…)” (p. 39).

There are several other interesting bits of information in this excellent, rare interview (buy the book if you can!). But these small references provide extremely fascinating clues to the placement of the novels and short stories. That the original production team decided to place the stories in 1936 does not really come as a surprise. After all, this is more or less common knowledge by now. That they admit placing episodes outside the 1936 time frame is another matter. Not surprisingly, I find it hard to believe Eastman’s “within a twelve- to fifteen month period” as the limit of their placement of episodes. I’ve found specific 'evidence' to prove that episodes were deliberately placed as early as June 1934. 

However, the most intriguing information in this interview is arguably that Eastman, Exton and Suchet actually planned to move the series onwards in time, to the 40s, 50s and 60s! Obviously, this would have made the feel and look of the series completely different – and a chronology of Poirot’s life would have been as unbelievable as in Christie’s original stories (possibly even more unbelievable, as aging on screen and aging in text is visually very different. The post-Eastman producers must have had radically different views on the development of the series, as we (since 2004) have seen that several novels have been moved from their original post-war setting (e.g. The Clocks, Third Girl) to a pre-war setting in the TV series.

My findings – some clear patterns

There are a few patterns evident from my “research”:

1)      Several episodes (18) do not contain references (see previous post).

2)      Several episodes made before 2004 have been consciously placed outside the 1936 time frame (1934 and 1935)

3)      Of the post-2004 episodes, several (6) do not contain references, while those that do more or less exclusively refer to dates outside the 1936 time frame (1937 and 1938, possibly 1939 and 1940).

4)      It seems probable that the current producers are aiming at a conclusion of the series directly after the Second World War (Curtain), making Poirot’s on-screen timeline both significantly younger and, arguably, significantly more believable than Christie’s original. The fact that Poirot is younger is also commented on in Peter Haining’s book (see below). As I’ve stated earlier, I see Poirot as being probably around 40 when arriving in England and around 60 in the majority of the episodes. I imagine him to die around 1945-50, aged around 70.

“What was altogether different about this episode [The Mysterious Affair at Styles] was that the little detective was now a younger man (…) [David Suchet’s] head was partially covered with a new hairpiece to make the immaculately groomed hair look thicker” (p. 27).

A note on the producer's chronology
It seems evident to me that the producers have had some sort of chronology in mind, as is evident from the above mentioned quotes and countless interviews with David Suchet. In short, I think this chronology plays out more or less as follows:

1934-5: Most episodes of Series One-Three. Poirot in Clapham Cook (1935) is at the height of his career. He lives in Whitehaven Mansions, employs Miss Lemon (and possibly Hastings?).

1936: Most episodes of Series Four-Eight. Hastings meets Bella in Series Six (1995-6) and returns in Series Seven (2000), having lost his ranch in Argentina. He visits his cousin in Mesopotamia in Series Eight and has since disappeared from screen (supposedly he's back in Argentina).

1937-8: Most episodes of Series Nine-Twelve. New producers arrived, and the decision to move on in time must have been made almost immideately. Poirot is now living alone with his manservant George.

(See also the page 'Episodes', where I have listed all episodes in viewing order with chronology references).

While I make no attempt to hide my disappointment with the script writers and producers as to the chaos they've created in terms of chronology, I still acknowledge that this chronology (almost) works. It does, however, require any eagle-eyed viewer to ignore all references to setting - or regard the timeframe as a very "floating" mid-to-late 1930s setting.

Denouement

I’ve learned a lot about my favourite television series through this little project. It’s been exciting to sort out the quirky little details, even though I've really been struggling with some of them. And I might not be completely done yet; there are still some I am very uncertain about. So things might change. And anyhow, I’ll probably have to place coming series in the chronology as well (I’m really hoping for news on a new series soon!).

My hopes for the coming series are that the producers and writers will bring the series to a reasonable end. I hope they continue what seems to be a conscious decision – to place episodes in the post-1936 time frame. Hopefully, some of the stories to come – like The Big Four and Labours of Hercules – are placed directly preceding World War II; between 1938-1940. Then, Curtain, the final novel, will be set alone in the mid-to-late 1940s – almost ten years after the others. That would, in my opinion, give the series a decent and reasonable conclusion. (This does, however, require them to change the character of Judith Hastings in Curtain, as she would be about ten or twelve years old in a late-40s version of the story! Perhaps she could be Hastings's niece instead of daughter?)

Finally, let me conclude by saying that it is my genuine wish that this blog will serve as an inspiration and a source of information for all other Poirot fans. I would reccommend reading the posts in publication order - from the first to the last post. This will make it easier to follow the references I make to other episodes in the chronology.

I kindly ask that you will respect the work and effort I have put into this project by asking for my permission (leave a comment) before taking any of the information on this blog for your own use. Thank you.

EDIT:  I just want to clarify that this blog will not be updated, unless I discover any mistakes, uncovered areas etc OR new episodes are produced. The blog is intended to be an "encyclopedia" of 'Poirot' chronology and will not be developed further from the basic posts already on here. Comments are, of course, more than welcome.

CHRONOLOGY: 1949

OCTOBER: Curtain: Poirot's Last Case

Poirot's letter to Hastings reads 'October 1949'. However, Hastings has a grown-up daughter, Judith, and that shouldn't really be possible. He met Bella Duveen, his wife, in 1936. That would make Judith 12 or 13 years old - if she was conceived and born immediately afterwards. The reference to the year can't be ignored. After all, the episode is obviously set soon after the war; Styles is in decay and Hastings mentions the rationing. 

The only possible solution here is to explain Judith's age by making her Hastings' adopted daughter. As always with these compromises, this isn't a perfect solution, but I think it works. I'lll try to explain:

Let's imagine that Hastings (or Bella) was sterile, and they wanted a child. They adopt Judith, an orphaned young girl of seven or eight, possibly when Hastings returns to Argentina in 1937 after his brief visit to England in the summer. This would also explain her Englishness, if she was schooled in England, and decided to go back there after the war. Hastings makes a brief return to England for Poirot's 'funeral'. Poirot doubtlessly sent Judith presents and cards for Christmas, birthdays and every other occassion, and her father is bound to have been talking about his adventures with Poirot almost non-stop, so this would explain her 'Uncle Hercule' comment. She feels as if she knows him like a member of the family.

Hastings is a kind-hearted and caring man. He would love Judith like his own flesh and blood. Also, Poirot biographer Anne Hart has suggested that Hastings might himself have been an orphaned child:

'We know that he went to Eton, but the only member of his family ever mentioned is his great-aunt Mary (...) It is possible that Hastings was orphaned at an early age, for one of the first things we learn about him is that he had 'no near relations or close friends'. Perhaps great-aunt Mary had been his guardian?' ('The Life and Times of Hercule Poirot', p. 156)

Hastings' comment after Poirot's death (in the adaptation), that Poirot had been like a father to him, also seems to support the claim that he was adopted. If we are to accept this theory, it would be even more natural for Hastings to adopt a daughter. He knows what being an orphan entails. It would also add to him feeling so protective of her; he really wants her to do well in life.

This isn't ideal, but it's an acceptable solution to a fairly obvious chronology issue. After  all, the producers could have no idea when the series began in 1989 that it would be running for 25 years within the same setting (late 1930s) and that there would then be a need to explain Hastings' daughter in the final adaptation.

CHRONOLOGY: 1946

APRIL: The Labours of Hercules

I expect this will be a somewhat controversial placement. The episode offers two impossible challenges. First, Countess Rossakoff mentions in her first conversation with Poirot that it's been twenty years since they last saw each other. Second, Rossakoff has apparently had a daughter in the intervening years, Alice Cunningham, who is now in her twenties.

Now, the last time Poirot and Countess Rossakoff met was in The Double Clue. I've placed that episode in 1934, mainly because Rossakoff mentions the new age of Stalin and Hitler (and Hitler didn't assume power until 1933). It's almost impossible to make the gap between this episode and The Labours of Hercules 20 years. Thankfully, a reader of the blog, Zaa, told me that the words "twenty" and "twelve" look and sound remarkably similar in the Russian language ('двенадцать' for twelve and 'двадцать' for twenty). According to him, it's perfectly possible that Rossakoff mixed up the two words in English and said twenty instead of twelve. Add to that the character's tendency to exaggerate, and it's conceivable that the mention of twenty years was either a word slip or an exaggeration, or both.  In any case, I like the idea of the Russian language as the reason behind the exaggeration. Russian was the solution to the cigarette case  in  The Double Clue, so it's neat to make Russian the answer here as well.

Since The Double Clue ideally should be set around 1933, the likely candidate for The Labours of Hercules would be 1946, immediately after the war. There's no mention of how much time has elapsed between this episode and the previous one in the chronology, The Big Four, so it's perfectly possible that the war has occurred in the intervening years. As biographer Anne Hart has established, Christie rarely mentioned the war in her war novels, so it's not unlikely that there are no references to it here; the actual collection of short stories was published in 1947, and there are no references to the war in it. Also, Dr Lutz is quick to establish that he is 'not a Nazi' in his conversation with Poirot. This could imply that he is anxious to distance himself from Germany's immediate past (suspicions towards Germans and Austrians in the immediate post-war years were not uncommon). In other words, there's a possible war reference here if you want to emphasise that.

The remaining issue is Rossakoff's daughter, Alice. She is definitely in her twenties, which wouldn't make sense given the setting for The Double Clue. In my opinion, the crucial point is Rossakoff's character. She is known as a compulsive liar, and she is very vague on both her own and Alice's origins. I think it's likely that Alice was born years before the Countess met Poirot. She might have been placed in an orphanage (which would account for SPOILER her evil nature later in life), or she has been cared for by Rossakoff's family members. It's not unlikely that Rossakoff omitted to mention her when she first met Poirot, because she knew she could use his infatuation to escape justice - just like she tries to persuade him SPOILER to let Alice escape justice in this episode.

Of course, neither of these decisions (placing the episode after the war, explaining Alice's background) are perfect, but I think this is the most reasonable explanation for an inexcusable error on scriptwriter Guy Andrews' account. 

CHRONOLOGY: 1939

MARCH/APRIL: The Big Four
I haven't seen this episode myself yet, but it has aired in Poland (October 2013). Thanks to a Polish fan, ueetba, I can place the episode in March/April 1939. In other words, this is as far as we can be certain the Poirot series has come. Ueetba has kindly provided the screencaps below. He also tells me there's no specific references to how long Hastings, Japp and Miss Lemon have been gone from the series, nor is there any explanation as to what they've been up to. Thankfully, this means that a 1939 setting, about two years since we last saw them (in chronology terms) would work.

 One of the first things we see in the episode is a letter received by Hastings in Argentina (see above). The post stamp clearly gives the date "20 APR 1939".

 After the initial prologue, which includes the letter to Hastings, a caption reads "Four weeks earlier", which leads us back to early March.

 Later in the episode, Flossie Monro receives a boquet of flowers. According to ueetba, this is in April. The action soon returns to the events of the prologue, which is set in April (as we established with Hastings' letter).

 Finally, a theatre that features prominently in the episode had it's last repertory season in 1924. Flossie Monro explains that this was "fifteen years ago". That gives us the year 1939.

MAY: The Clocks

Several things point towards a late-1930s setting for this episode. Colin Race and the Navy are turning the tunnels under Dover Castle “into a bomb proof HQ were things to come to a second war with Germany”. According to Wikipedia, the conversion of the tunnels took place just before the outbreak of the war in 1939, and they were used in military operations the following year. The Waterstones (the Jews) “came over in 1936 from Munich. They changed their name from Tuchmann”. Moreover, when arrested, Mr. Mabbutt says the following: “If Chamberlain’s policy of appeasement doesn’t hold and someone like Churchill (assumed office in May 1940) gets his hands on power, we will be dragged into a war a hundred times worse than the last one!”.

The episode is probably supposed to take place in spring 1938, as Chamberlain did not sign the Munich Agreement until September 1938. When this failed, he began to prepare for war. So it could take place in spring 1939 as well. A matter of choice, I guess. Since the conversion of the tunnels was completed by the end of 1939 (according to Wikipedia), I’ve chosen to place it in May 1939.

CHRONOLOGY: 1938

JANUARY: Murder in Mesopotamia

Frederick Bosner's execution is reported in a newspaper dated November 1918, and that was "nearly twenty years ago".  Captain Hastings says he's been married "a few years", which is pushing it a bit considering when the production crew decided to set Murder on the Links, but it might reasonably be 1938.  So this could be the latest pre-2004 adaptation in chronological terms.  Moreover, in Christie’s novel, Nurse Leatheran mentions that “M. Poirot went back to Syria, and about a week later he went home on the Orient Express and got himself mixed up in another murder”, so the episode should (and could, incredibly enough) be placed directly preceding Murder on the Orient Express. So I would say the case itself is set at some point in late December 1937 and early January 1938.

JANUARY/FEBRUARY: Murder on the Orient Express

I’ll lean on a comment from one of the excellent users of the forums at the Agatha Christie page, shantysleuth, who put my sentiments on this episode to the point:

“I think there is an error in MOTOE. It's definitely set in 1938, but the actual month is either September or January. Poirot receives a telegram from London while at the hotel in Istanbul, and it is clearly dated 26/9/38. However, a closeup of Ratchett's note telling him to drop the ransom money off at Calais reads January. I think January is correct, but how the filmmakers could be so careless as to show a closeup of an incorrectly-dated telegram is beyond me.”

In other words, I choose to set MOTOE in January/February 1938, directly after Murder in Mesopotamia.

FEBRUARY: Elephants Can Remember
The episodes opens with a caption reading "1925". Then, the action shifts, and the caption reads "Thirteen years later" (see temporary screencaps below - will upload higher quality when the DVD/Bluray set is released). As a result, the episode is quite clearly set in 1938. I am delighted to see that they 've kept going with the (conscious) move to 1938 that began with MOTOE (see above). May the remaining (as of June 2013) four episodes continue in that fashion!

JUNE: Dead Man's Folly
No references. Mrs Oliver eats apples, a habit we know she stopped in Hallowe'en Party (the novel), set in October this year. The friendship between Poirot and Mrs Oliver is well developed here, so you would assume that they have cooperated on a couple of cases already.

 

JULY/AUGUST: Three Act Tragedy

No references. George is present, so it must be after Taken at the Flood. There are also several hints to a placement after 1936. Le Train Bleu is used to Monte Carlo (my guess would be after Mystery of the Blue Train), and most of the people don’t know who Poirot is; Charles Cartwright introduces Poirot to Miss Wills as a detective (“a real one?”), making it reasonable to believe that his fame is declining (possibly as a result of his semi-retirement). The story takes place over at least two months, as a card between the first murder (Babbington) and the second murder (Strange) reads “one month later”. It looks like summer.

© ITV

SEPTEMBER: Cat Among the Pigeons

No specific references. A football game between Arsenal and Sheffield United is mentioned, but that took place in APRIL 1936, as far as I’ve been able to ascertain.  This episode is supposed to be set at the beginning of the school term (September?). George is mentioned (helping Poirot by telephone, packing case etc.), so once again this has to be placed after Taken at the Flood. Julia Upjohn, the girl, mentions one of Poirot’s cases where someone has their head smashed in. This could be Mrs. McGinty, but I’m guessing Enoc Arden/Charles in Taken at the Flood. In this episode, Spence and Poirot speculate on suicide, but regard it as unlikely to be “smashing in the back of one’s head”. Ramat (the Middle East country mentioned) does not exist. I choose September 1938.

© ITV

SEPTEMBER: The Hollow

The dinner invitation Lady Angkatell sends Poirot is dated 'Saturday 17th September'. 1938 fits this date. Lady Ankatell also mentions Poirot’s case in Baghdad (something about him being ”talked about all over Baghdad” when "Henry was High Commissioner"). This somewhat fits with Murder in Mesopotamia in January 1938, if we assume Henry has just retired. Unlikely, but possible. No mention of George or the new apartment (we don’t even see Whitehaven Mansions). So it could theoretically be set before or after Cards on the Table and Taken at the Flood. Based on the evidence of the date, however, I choose to place it in September 1938.

OCTOBER: Mrs. McGinty’s Dead
Poirot tells Mrs. Carpenter that the murder “occurred last November, the 22^nd.” Mr. Upward states “but surely, that’s all over now”. Mrs. Carpenter can’t remember Mrs. McGinty’s name, even though “she worked for you here in this house?”, as Poirot points out. She answers that “She didn’t. I wasn’t living here then. Mr. Carpenter and I were only married three months ago”. Furthermore, Mrs. Summerhayes says she bought the sugar hammer at Christmas, while Mrs. Rendell claims it happened at the harvest festival in late September (a matter of importance, because it could then have been used as the murder weapon). 

In other words, everything points to Poirot investigating the crime almost a year after it actually took place. The newspaper Mrs. McGinty reads is dated "Sunday, November 19", and the murder took place on Wednesday 22^nd. The only year to fit the dates is 1939. Furthermore, the newspaper with the verdict (shortly before Spt. Spence's visit to Poirot) is dated "Sunday, September 29". The year 1940 fits the date. This means the investigation would have to take place in 1940, which might be seen as rather unlikely. On the other hand, Poirot’s moustache looks thinner, and hardly anyone remembers him or his name. So his fame is declining. In other words, perhaps a 1940-setting could fit. As for no mentioning of the war; Anne Hart states on p. 81-82 in her book that there is hardly any evidence of wartime in either Poirot or Marple stories:


”(...) where in this decade, one may very well ask, is Poirot and the Second World War? There had, after all, been forebodings of events to come in several of the cases of the late 1930s (…) As is the case with Miss Marple in wartime, we are told practically nothing of Poirot’s activities. (…) Whether as a smokescreen or not, Poirot remained in his flat in London and continued accepting cases. Those recorded for posterity have nothing to do with the war.”


I leave it up to you to decide whether you will lean on these dates and place the episode in 1940 or ignore them and place it in 1938 (or 1939, for that matter). I've decided on 1938, because that works better with the other Ariadne Oliver stories.

Now, someone in the comment section pointed out, as I am already aware, that a) Mrs. Oliver (or rather Mr. Upward) is planning a stage version of one of her Sven Hjerson novels, and we see a Sven Hjerson play in the opening of The Clocks, set in 1938 or 1939, and b) Mrs. Oliver still eats apples in this episode, but in Christie's novel Hallowe'en Party, she is so traumatized by the brutal murder of Joyce that she promises never to eat an apple again (this is not in the adaptation of the novel, probably set in 1938, so TV-Ariadne and Book-Ariadne could easily have different sentiments on this particular fact). These two facts might suggest that the story is supposed to be set in 1938 (which, in any case, is the most likely option, even if the dates don't match). However, after the trauma of trying to adapt a novel into a play with Mr. Upward (who SPOILER! even turns out to be the killer), the play we are witnessing in The Clocks is certainly not Upward's Hjerson play, and probably not anyone elses either, really. (Unless Mrs. Oliver was tricked into it in one of her more scatterbrained moments!). Also, as to the apples, we still haven't seen her dislike of apples on screen. We'll have to wait and see, but somehow I doubt that fact will be included, since it wasn't mentioned in the adaptation of Hallowe'en Party. Still, I do think a 1938 setting is much more sensible than 1940, so unless the entire chronology is ruined by the final five adaptations of Series 13, I am inclined to make a final placement of it here. 

OCTOBER/NOVEMBER: Hallow’een Party

No references. Both Mrs. Oliver and George are present, so it has to be set after Taken at the Flood and Cards on the Table. And for once, we actually know how long the case lasts: The murder of Joyce is on October 31^st. The day before the last day is Guy Fawkes Night (scene between Michael and Mrs. Drake), November 5^th. Then there is one more day for investigation and denouement. I find a late 1938 setting likely, since 1937 is filled up with Mrs. Oliver’s cases already.

EDIT: As you can see in the comments section, the next to last day is not Guy Fawkes Night (Michael says "Guy Fawkes Night is almost upon us"), but the adaptation is still reasonably set within one week.

© ITV

CHRONOLOGY: 1937

JANUARY: Appointment With Death
 
The on-screen caption reads "Syria 1937". My guess would be January, simply because Death on the Nile was placed in January 1936 (and I find it likely that Poirot would escape the English winter for a warmer climate, e.g. because of his obsession with central heating, see Hercule Poirot's Christmas).

MAY: The Mystery of the Blue Train

Mirelle Milesi’s ticket for The Blue Train is dated “17 MAY 1936”.  It has to precede Murder on the Orient Express, because the following exchange takes place between Katherine Grey and Poirot:

Katherine Grey: I’m going to go to Vienna, I’m picking up the Orient Express. The idea thrills me. But I expect you’ve been on it millions of times.

Poirot: Not once. But I must!

This certainly points towards a 1936-setting. The problem is, though, that FIVE other episodes should ideally be placed in the exact same month/week/day (see this post)! In an attempt to solve this intricate problem, I’ve decided to move the adaptation one year forward, because the episode fits better in with the post-Hastings time period of Poirot’s life – and the post-1936 chronology of the new producers.In any case, I would put this error down to the production designers rather than the script writers, as this ticket is the only evidence of an intended 1936 setting

JUNE: Five Little Pigs

I can't see the year on Lucy Crale's letter to Poirot, but it's dated '7th June' which gives us a time of year to work with. The murder is said to have happened 14 years earlier, and the archive newspaper Poirot looks at is dated "Thursday, May 3". If we start by assuming another late 1930s setting for "the present day", we find that the best fit for Thursday 3rd May is 1923.  So I reckon the story itself is set in June 1937.

JUNE/JULY: Lord Edgware Dies
 
Carlotta Adams’ letter is dated June 29^th 1936, and Hastings says of a date on a box (November 10th): "that's seven months ago!". We see Miss Lemon’s case files being returned to the apartment, and Poirot stating “Have the final cases arrived?”. Yes, I know this sounds like they’re moving in again (see The Murder of Roger Ackroyd), but this is never actually mentioned explicitly. I choose to imagine that the files have just been stored up somewhere while Poirot's office has been rented out during his six month semi-retirement (see 'Hercule Poirot Timeline'). Poirot cooks dinner and tells Miss Lemon it’s “a dish that I discovered during my retirement”. This can quite as easily be several years ago, as I have chosen in my chronology (see 1933 post), or possibly on one of his journeys abroad in semi-retirement that year (see 'Hercule Poirot Timeline').

The Hastings Storyline: Hastings returns to Britian having lost the farm in Argentina (bad investment in a railway company).  Hastings explains: “poor Bella stayed behind to sell the ranch. I’ve come here to find somewhere for us to live … if I can afford London prices”. At the end of the episode, Hastings receives a cheque from the Duke of Merton (judging by the look on his face, it's a substantial amount of money):

Hastings: But shouldn’t this be made out to you?
Poirot: Oh, non, non, non. It was you who provided the clue that was vital.
Poirot (after some time): It should be sufficient, mon ami, for you to purchase an apartment in London
Hastings (after being fooled by Poirot, Japp and Miss Lemon): You know, I think I’ll put this in the bank.

In my chronology, this fits with Hastings having returned in 1937. He uses the money from the Duke of Merton – either to buy back the farm in Argentina, or to buy back his Argentinean restaurant in London (see Evil under the Sun), depending on how large the amount of money was. Personally I would go for the former option, leaving Poirot alone from July 1937 onwards. (see 'Hastings Storyline').