Further to the thread re concertinas at Witney, there is also Melodeons at Witney, exactly the same but for melodeons. info at
http://www.whitecottagewebsites.co.uk/homweekends/melodeons.htm
I dont know how to do blue clicky things so you might have to copy and paste into your browser.
run by Dave Townsend's Hands-On Music Weekends organisation.

Black Diamond