progdirjim
Larry Mitchell
James East
Nathan East
Bryan Ferry
Roxy Music
Eddie Jobson
Jethro Tull
Clive Bunker
Aviator
Mick Rogers
M.M.E.B
Chris Slade
AC/DC
Angus Young

The extra credit is a tricky one.

I've got:
Chris Slade
Uriah Heep
John Wetton
Asia
Greg Lake
King Crimson
Robert Fripp

But we could miss out the Asia-Lake link and it would still work.

Edit:

Just checked Chris Slade did tour with Asia. Also, Clive Bunker was in M.M.E.B for a while too. What an incestuous lot these Prog guys are!!!!

I think that Bob has it!!!!!

BTW: Appalling joke Rick.

Next day the same goat walked into another bar. He ended up in hospital as it was an iron bar