A blood-splattered copy of the ABC railway guide, along with a stocking, is always found at the scene of the murders, which follow the letters of the alphabet. Thus, Alice Ascher is stabbed in her tobacco shop in Andover; Elizabeth “Betty” Barnard, a flirty waitress, killed on the beach at Bexhill; and Sir Carmichael Clarke, a wealthy man bludgeoned with a spade in the grounds of his home in Churston. After a further murder in Doncaster, the scene is set for the serial killer to strike in Emsbay.

The adaptation, set in 1933 and with wonderful evocations of the days of steam trains, is directed by Alex Gabassi and scripted by screenplay writer Sarah Phelps. She has built up a reputation for changing the original plot of a novel — and sometimes, as was the case with another of Christie’s thrillers, Ordeal by Innocence, even the ending. In The A.B.C. Murders, she has kept to Christie’s storyline but her adaptation delves as deeply into Poirot’s background in pre-1914 Belgium, which he had to flee because of the country’s invasion by Germany, as it does into the actual crimes that take place.

It is fair to say the new Poirot has not met with universal acclaim from critics, reviewers and commentators.

Without giving too much away, there is a clue in the cross above his bed, where viewers see him first sitting with his head in his hands. His glory days are behind him, he is no longer sought by the titled ladies of the land for their country weekend parties, and he has fallen on hard times. Most wounding of all professionally, his best friend at Scotland Yard, Inspector James Japp (Kevin McNally), with whom he has worked closely for many years, dies at the outset of a heart attack. He is replaced by his unsympathetic deputy, Inspector Crome, who has little time for his late boss’s old friend.

To put Poirot’s career into context, he made his debut in 1920 in The Mysterious Affair at Styles and took his bow in Curtain, published in 1975. His “obituary” merited coverage in the New York Times and the Daily Telegraph. As one of Christie’s most enduring creations, he appeared in 33 novels, one play, Black Coffee, and more than 50 short stories.

He has been portrayed on radio, in film and on television by various actors, including Austin Trevor, John Moffatt, Albert Finney, Peter Ustinov, Ian Holm, Tony Randall, Alfred Molina, Orson Welles, David Suchet, Kenneth Branagh and, lastly and perhaps most controversially, by Malkovich.

To the average British viewers, Suchet, who appeared in 70 episodes as Poirot, made the character his own with his distinctive walk, fastidious manner and references to his “little grey cells”. All this has been cut out from Malkovich’s Poirot, along with Suchet’s carefully tended moustache.

Phelps has woven something of the anti-foreigner sentiment around the contemporary Brexit debate into the dialogue.

“Nineteen years I have lived here (in England) and people still think I am French,” an exasperated Poirot comments at one stage.

A ticket inspector checking his ticket on a train deliberately drops it on the floor forcing a weary Poirot to bend down and pick it up. At another point, Poirot rips down a British Union of Fascists poster declaring, “March for England. We Must Stem the Alien Tide.”

One of the BBC’s much anticipated offerings over Christmas was a three-part television adaptation of Agatha Christie’s 1936 crime thriller, The A.B.C. Murders, with the distinguished 65-year-old American actor, John Malkovich, cast as the Belgian detective, Hercule Poirot.

Another revelation is seeing Rupert Grint, now 30, cast as the Inspector Crome, who so mocks Poirot for dyeing his white goatee a dark shade that the detective goes back and washes out the colour. The water slowly turning black in the sink is a metaphor for the dark mood of the adaptation.

It is understandable if viewers do not recognise Grint for nearly two decades have passed since he was cast at the age of 11 as Ron Weasley in the Harry Potter franchise. He starred in all eight Potter films, which concluded in 2011.

Suspicious of Poirot, Crome does a background check and cannot find evidence he has ever been a policeman in Belgium, although Christie had made him head of the force. “Who the hell are you?” he confronts Poirot, determined to cut him out from investigating the A.B.C. murders.

“My name is Hercule Poirot,” he mutters to himself. “I am a refugee.”

According to his adaptation, he had of all things, been a priest, who had been tormented by his failure to save his parishioners from being slaughtered by the Germans after the villagers had listened to his advice and sheltered in his church.

In one interview, the Oscar-nominated Malkovich said he took on the role of Poirot because he found Phelps’ scripts “were very well written, the character was interesting, Hercule Poirot was perhaps not very happy and in a phase of his life that we don’t see very often and isn’t dramatised very often and that is what interested me”.

He was drawn by “where Hercule Poirot is in his life; he is nearing the end of his life, he is quite forgotten. As it happens he has lived in England for almost two decades and the world has passed him by. As well as the plot and a lot of very good characters, that was the part that interested me the most.”

Malkovich said he was no expert on the early 1930s “but certainly everybody, myself included, has felt exile; has felt an outsider; has felt unwelcome in various places and situations. I think Sarah (Phelps) draws interesting parallels with today. I don’t think it’s easy to be an immigrant.”

Poirot with Inspector Crome (Rupert Grint) at Doncaster railway station Image: BBC Pictures