Phil also sings with Pete on The Colony Of Slippermen. He's especially notable on the line "Where the raven flies, there's jeopardy".
Correct -- that brief line ("now can't you see, where the raven flies there's jeopardy") is Phil's one definite lead vocal on the album! And I couldn't tell you how many times I heard the song before I noticed that...
He's also very prominent on "The Supernatural Anaesthetist" and could be considered "second lead" on that one as well.