the occasional new tune is a bonus to keep stretching people and improving people's repertoire

I do agree - otherwise you could end up with a room full of people who can play Buttered Peas at warp speed but can't play anything else. We're up to 52 tunes now (I'm not sure we've ever got as far as number 52) and the next version of the book will be bigger again. (I say 'we', although I'm taking a break from tunes sessions at the moment while I get my whistle up to speed.)

We've had several tunes start as something somebody played for their own amusement in the half-time break and end up as core to the repertoire - John Fenwick's, Le Canal en Octobre and the Dusty Miller to name but three. (I saw the D. M. written down before I'd ever heard it; I drew the wrong conclusion from the time sig. and learned it as a slow air. I got the shock of my life when I heard it played.)