Grand National Night (1953)

After race horse trainer Gerald Coates' (Nigel Patrick) horse wins the Grand National, his wife comes home drunk, and the two of them have a violent argument, and she is accidentally killed. Coates insists that she didn't come home after the big race, but the police begin to suspect him, after a train ticket is found in his coat. About to be arrested, he receives help from an unexpected source.

https://www.imdb.com/title/tt0048132