with Steve Colman and Peter Simon
Who am I? I sport a natty line in waistcoats. You have to get 'green for go' to break through my wall. I always line up lots of mystery people and objects behind my door. If you can't guess, find the answer by watching today's Knock Knock!
Written by JOHN PALMER Designer HERBE GEORGE Executive producer
CHRISTOPHER PILKINGTON Production SALLY FRASER