I'm not sure whether this falls within your remit Geoff - essentially it is an American collection, but it contains a great deal of British and Irish material

HELEN HARTNESS FLANDERS COLLECTION

The recordings are not great, but many of the songs are invaluable - from a couple of singers in particular
I have found it invaluable during my searches for Irish versions of Child ballads

I'm sure you are aware of the Goilín and Inishowen collections on line from the Irish Traditional Music Archive
ITMA has recently put up a collection of Newfoundland/Irish singers - I passed that on here a few months ago
All these are well worth a listen

Somewhere I have a link to the John Reilly recordings on line, made by American researchers, D K Wilgus and Eleanor Long - there are other important Irish recordings included there

The Ken Goldstein collection, including recordings of Lucy Stewart, is available only to students - I'm hoping that changes soon
Best
Jim