Mike Oldfield had Maggie Reilly singing on many of his albums as well as his greatest hit singles (Moonlight Shadow, To France, Sheba, etc.)
Not really prog, more straightforward rock...
Slack Alice (one album only, but great fun!)
Stone the Crows
FRANKIE GOES TO HOLLYWOOD - 'Welcome to the Pleasuredome'
You either love it, or you loathe it.
Me? I love it!
So many driving, pumping tunes in those massive hit singles.
Trevor Horn - what a producer (and performer!)