Another follow-up from me to say a big thank you to Jim. I found there was a copy of the song book on eBay for £5 inc p&p, and forwarded the link. The producer (of a show called Putting on the Blitz) has now bought the book and looks foward to discovering the tune! Even if it turned out to be a different song, it would almost certainly be useable, as may some of the other songs in the book.
Thanks again,
Marje