this is for old primary teachers
When I was at school in England in the 60s we had a series of songbooks of folksongs, mainly from the British Isles. They were A5 size, soft back in a funny non smooth cover, in such 60s colours as lime green, orange, turquoise, they had I think both stave and sol fa. There must have been a piano version.
Do they ring any bells? It was an excellent collection.