I also saw Spoon, but in the 60s. It was in a jazz pub in Leeds called the Peel Hotel.
I did quite well for classic male jazz vocalists. I saw Joe Turner (in a blues package), Jimmy Rushing (with the Humphrey Lyttelton band) and Joe Williams (with Basie).
I also saw Mark Murphy (at Ronnie Scott's), though of course he was a very different sort of vocalist.