Steeleye Span with Peter Sellers: New York Girls

What was Peter Sellers doing playing the ukulele on a track on Steeleye Span's 1975 album Commoners Crown ? Maddy Prior explains: While sitting over lunch we were discussing what we need to sparkle up the track New York Girls. Ukulele would be good someone said. Anyone got one? Anybody know someone who can play one? Peter Sellers plays it says Bob. Pause. Eyes meet, why not? We could ask. He could…