After a few years gap - I knew Ralph in London in the 1980s, he was a lovely chap and a good friend and played concertina at my farewell party in March-April 1986 at the Grafton Arms when I was departing for Australia, where I have resided since (I have a tape of the night somewhere, should dig it out).
The main reason for this note is that I have recently been digitising some of my folk-related photos from that and other eras, as noted on this other mudcat thread at https://mudcat.org/thread.cfm?threadid=165268, and have included some images of Crows (including Ralph) taken at Towersey Festival in 1980 and in London in 1983. If interested, you can see these via https://en.wikipedia.org/wiki/User:Tony_1212#Music_related_2 (scroll down a bit to see them).
I never knew Sheena but hope she may enjoy these few images (I probably have some others too that I can dig out if you like).
All the best from Tony Rees, NSW, Australia.