I've just finished watching a BBC Scotland programme about Jimmy MacGregor at 80, which had some old B&W footage of him performing with Robin Hall, and there were some shots featuring Brock, pipe clenched between teeth, playing bass.

I remember working as a cameraman on various TV programmmes such as The McCalmans in the BBC's Glasgow studios when he was the bass player, the butt of Ian McCalman's wry sense of humour, but happy to chat with the crew during rehearsals.