thank you for your comment. Would you happen to know when the first Bagnall locomotives were brought into Japan?
Sorry Fred, no. But the archives of W.G. Bagnall are held here,
http://www.staffordshire.gov.uk/leisure/archives/homepage.aspx. If you're interested in further research that would be the place to look. They hold "19th-20th Cent: financial records, valuations and inventories, registers of drawings, and locomotives built, drawings and blueprints, drawing microfilm negatives, production records, casting and patterns registers, manuals to individual locomotives, tendering, sales and orders records salesmen's albums...".
Well, finances and resources must have been tight in 1943. According to the information provided by bikkuri bahn, Kurosawa was only 30 years off --and: this was his debut film after he had worked many years as an assistant director and script writer.
Well, I was being a bit facetious.

The amazing thing to me is that he managed to make any sort of movie in 1943. And I don't mind seeing a Bagnall loco immortalised on film at all!
Cheers,
Mark.