In the novel 4.50 from Paddington, James Stoddart-West is a friend of Alexander Eastley. He goes with Alexander to Rutherford Hall. He has dark hair, and wears spectacles. Like Alexander, he has well-brushed hair, a suspiciously angelic face, and perfect manners.
James and Alexander set up a clock golf set on the lawn at Rutherford Hall. The numbers are rusty, so they and Lucy Eyelesbarrow go to the Long Barn to look for paint, to paint the numbers. This leads to Lucy discovering a woman's body in a sarcophagus in the Long Barn.
After the discovery of the body, James and Alexander beg Inspector Bacon to let them see it. They take a great interest in the case, riding their bicycles to the inquest, and searching the grounds of Rutherford Hall for clues. They find a torn envelope addressed to Mrs Martine Crackenthorpe, which they give to Inspector Craddock. This seems to suggest that the dead woman is Martine.
The day after discovering the envelope, James returns to his parents' home, and Alexander goes with him. They tell James' parents about the case, the envelope they found, and how it is believed that the dead woman is Martine. This leads Lady Stoddart-West, James' mother, to visit Emma Crackenthorpe. Lady Stoddart-West reveals that she was the Martine whom Edmund Crackenthorpe had written about, and that she had loved him very much.
Murder She Said
James Stoddart-West does not appear in MGM's adaptation Murder, She Said.
BBC's Miss Marple
In BBC's 1987 adaptation of 4.50 from Paddington, the part of Jame is played by Daniele Stroppa (credited as Daniel Steel). His parents Sir Robert and Lady Martine Stoddard-West do not appear in the adaptation and he is younger than in the original novel, being about eleven. He thus has a much smaller role, mainly as an onlooker into the events at Rutherford Hall. The plot twist involving his mother is not employed.
NHK's Agatha Christie's Great Detectives Poirot and Marple
In NHK's anime adaptation 4:50 from Paddington, the character's name is simply "James". His age is roughly sixteen, the same as Mabel West, which is closer to that in the original novel. The part of James is voiced by Masataka Nakai. In the adaptation, James has a larger role than in the original and has a slightly different backstory. He and his friend Alex play a part in helping to find the body. They meet Mabel who is practising her golf. They want to fetch a football from "the Leaky Barn" and Mabel goes along with them. After they collect the ball and leave, Mabel remains behind to explore the barn and comes across a sarcophagus with the body inside. Later, he, Alex and Mabel eavesdrop on Emma Crackenthorpe telling Dr Quimper that she had received a letter from one "Martine". Thereafter they find an envelope addressed to "Martine" in the waste bin, suggesting that Martine had come to Rutherford Hall. After James returns home, he sees his mother and asks about his past, as he knew that her mother's name was also Martine. This leads her to come to see Emma and reveal that she is in fact the "Martine" who married Edmund Crackenthorpe. He died shortly thereafter but by then she was pregnant, and James is actually Edmund's son. In the original Martine did not confirm that she had married Edmund, only that she had loved him. Nor did she affirm that James was Edmund's son.
ITV's Agatha Christie's Marple
In ITV's 2004 adaptation of 4.50 from Paddington, James is portrayed much like in the original. Here, his mother also reveals that she is Martine, Edmund's wife, and that James is Edmund's son. However, unlike the NHK anime version, in this case, it is not because James had overheard the Crakenthorpe's discussing the letter from Martine. Here, Miss Marple makes the connection simply because, rather implausibly, she had heard him speaking impeccable French. The part of James is played by Toby Marlow.