Thanks, Steve and Dick, and also Gillymor. I have swapped to lighter strings and also reangled the guitar. I seem to be OK while I'm playing but then in some fairly acute pain afterwards. I was playing at a private gathering this afternoon, and my right hand has had it for today, but my left just feels a bit tired. Funny because I'm left-handed, and I was painting all morning. This I suppose tells me to take Dicks advice and get some exercise going on the right hand thumb joints. (And then fill a bowl with warm water, and swipe the hair dryer!) Thanks again.