Leviathan:

We really liked this band at the Marquee in 1969. Hadn't a clue about the line up's names, but I do remember an excellent young guitarist with a lion's mane of hair. Powerful leads in a slightly Creamish vein.
"Delerium"'s web site helped out (as always!):

Brian Bennett - guitar
Stuart Hobday - vocals
Roger McCabe - bass
Gary 'Roscoe' Murphy - drums.

I found this snippet in the N.M.E. of April 19 1969:

Never saw those singles, but I imported their single "Flames" (Roscoe Murphy - Brian Bennett)/"Just Forget Tomorrow" (Stuart Hobday - Brian Bennett). ELEKTRA EKSN 45075 (1969).
 
A-Side: Enter an electric guitar solo: first frantic, then fluid, sensuous. And then the vocals.
Tempo changes, more guitar breaks. I like this guitarist!

B-Side: Gentler, less frantic, more thoughtful. More good guitar breaks...