Lesley, another Postman's Knock friend, sent me this wonderful Seventies Ladybird book on clowns. It's a great book that I've not come across before and I'm very touched by Lesley's kind thought -- thank you.
'valley' is a marked dip in a graph of the positivity of human reaction as a function of a robot's human likeness. A strange concept, but you can see how it applies to clowns.
Just to bring things back within the realms of sanity, I also found these ... lovely cushions:
here. There, nothing scary about that, is there?