Michael Rosen has been presenting a series this week during the afternoons on Radio 4:

"A series of five programmes on children's play in school playgrounds, as part of an exploration of the work of Peter and Iona Opie."

I caught a bit of one programme this afternoon. Experts include Georgina Boyes. Anyone interested in playground rhymes, clapping and skipping games may want to have a listen:

People in the Playground Revisited