Fluorescent tube lighting in Paddington underground station? In 1933? Only ref I can find is (google) "first commercial use in London UG was one station in 1930s". Was it Paddington?
When Poirot hears a phone ringing in the Tube station it is an American style ring, not the British Toot-Toot ring.
Near the end we see a London Underground station illuminated by fluorescent tubes, but these were not commercially available in 1933.
A middle-aged working-class police constable like Yelland would not, in 1933, caution anyone against "doing your own thing", as he does here with Poirot - the expression did not become common in British parlance (among young people) for another third of a century.
When Poirot is trapped in the deserted Underground station (unlikely in itself) he has arrived in a silver tube train of a type not introduced until 1959.
The locomotive hauling Poirot's train has the number 65894. This is British Railways numbering dating from 1947, while the story is set in 1933.
When the killer telephones Poirot at a callbox in Paddington Underground station, the telephone rings with an American-style single ring, rather than a UK-style double ring.
During the train journey to from London to Doncaster, the train travels over the Ribblehead Viaduct, which is around 90 further north.