Hate to break it but it's syd Roger and Rick who sing in corporal clegg
ok so it goes like this and i am 100% sure about that:
David: Corporal Clegg
David and Rick (and maybe Roger): Corporal Cleeeeegg
David: had a wooden leg
Nick: He won it in a war in 1944
David: Dear, dear were they really sad for me? Dear, dear will they really laugh at me?
and so on
David sang the lead vocal and he did backing vocals with Rick and Rog and Nick sang these verses: He won it in the war In nineteen forty four/ In orange, red, and blue, he found it in the zoo/He’s never been the same, no one is to blame/From Her Majesty the queen, his boots were very clean.