…here’s something he was doing in August 1970, with the Humblebums, on BBC’s ‘Sounds of the Seventies’, which I’ve just transferred from a reel. Three songs: Cruising (Billy Connolly vocal), Keep It To Yourself (Rafferty vocal, prog-rock epic), My Singing Bird (Rafferty again).
https://soundcloud.com/colinh-1/the-humblebums-sounds-of-the-70s-6870-3-songs