WANTED: British singers on 78s

[Crystalate]

I am interested in any 78s by the following British artists:
Vera Lynn
Jessie Matthews
Bob and Alf Pearson
Steve Conway

This includes vocal refrains, where they were the featured vocalist with a band, but either credited or uncredited.

I do have many of their 78s already, having looked in the usual places (eBay, Discogs, MusicStack). Chances are that if you have any, I'll have it already, but you never know. Vera Lynn 78s are very common, of course, but some are rarer.

If anyone has any, or knows of a good source for such records, do let me know please.