I'm looking for details of Peter Cook sketch from 1975 made for the "YES" or
"NO" campaign on common market membership, to use in a modern TV documentary
on the history of the UK's relationship with the EU. Peter says If we sign up, snakes will invade the UK! Richard Littlejohn (who is a comedian but isn't funny) referenced it in a column but I've found no more detail

It might have been audio only (put out on a private eye flexi disc and included in this Guardian CD collection from 5/11/11 http://www.theguardian.com/media/2011/nov/05/offer-private-eyw. I'm
already investigating here) but I've been repeatedly told it was a TV
broadcast. Has anyone any ideas? And then of course I need copy good enough to show on TV.....