In the novel Sleeping Murder, Major Richard Erskine is a married man who met Helen on the ship to India, when he was travelling alone. They both knew their strong attraction had no future, so gave it up.
BBC's Miss Marple
In the BBC 1987 adaptation of the novel, Erskine is portrayed by John Bennett. Here he becomes a colonel instead of a major. The portrayal is highly faithful to the original novel.
ITV's Agatha Christie's Marple
In the ITV 2006 adaptation of the novel, the character becomes "Dickie Erskine", portrayed by Paul McGann. His backstory is changed drastically. Here he becomes the head of a troupe of performers named "The Funnybones" who came annually to perform at Dillmouth during the 1930s. Many of the main characters in the original novel have their backstories changed and become members of the troupe.
In this adaptation, Helen Marsden is a singer in the Funnybones. She becomes engaged to Kelvin Halliday but she disappeared the night before the wedding day. Thereafter the Funnybones troupe broke up. Unlike the original where the Erskines lived in Northumberland, here, at the time of the events in the episode during the 1950s, Erskine continues to reside in Dillmouth with his wife Janet and they have a son George Erskine. They live in a building named "Dunlaughin". It used to be the digs of the Funnybones. But after the war they bought the house over and appear to be running it as a boarding house or small hotel.
In speculating on Helen's disappearance, Erskine though Helen had run off with Jackie Afflick--he had seen him trying to persuade her. Jackie Afflick on the other hand, opined that Erskine killed Helen. The Funnybones was his whole life and Helen was their star attraction. Her departure because of marriage spelled the end of the troupe and he would have felt sore about it. Chief Inspector Primer also considered Erskine a suspect in the murder of Lily Tutt. This was because Erskine had a wife before Janet but she had left him and had gone on and married a crofter in the outer Hebrides. This sounded implausible and Primer had a hunch Erskine might have killed her because supposedly she couldn't bear children. Lily might have known something about this and he killed her to cover it up. However Primer checked up on the first wife and found that, unlikely as it seemed, it was all true and moreover, and that she had six children with her second husband.
In the 1950s, Dickie Erskine wore an eyepatch over his right eye, probably a result of the injury sustained when Jackie Afflick punched him years earlier. See Janet Erskine for details.
NHK's Anime adaptation
In NHK's anime adaptation of Sleeping Murder, the character becomes "Captain Erskine" and is voiced by Leo Morimoto, one of the few voice talents who actually gets credited.