I first heard ISB on John Peels radio prog, must have been 1966. We'd just returned from a 3 year posting in Singapore and I was 12 yo. I think it was This Moment Peel played and the sound was so new to me I was transfixed.
I only saw them once, the Lincoln Folk Festival in 1972 or 3. Tim Hardin was on and Tom Paxton as well.
The ISB albums sit quite happily with Cat Stevens.
The only other track I remember from that John Peel show was by a chap called Wild Man Fischer. I young Cliff Richard fan had been changed forever by just one radio programme !!!
Cheers
Gary