The musicians both seemed to be having a great time. One was a double bassist and the other was a guitarist who looked a bit like Frank Zappa wearing a Mike Nesmith hat. I originally thought they were improvising, but noticed that they were actually paying close attention to a music stand, and the sheet music thereon. The double bassist was concentrating particularly hard and I was impressed by the way he managed to smile and frown at the same time (not easy).
They had a break, returned to their instruments and for all I know played exactly the same set again. This time however their efforts earned deserved applause after every piece from the diners who by now didn't have to go the effort of putting down their knives and forks to show their appreciation. I wondered whether the musicians were enjoying themselves as much as they appeared to be. The easist way to find this out would have been to ask them, but I didn't. Maybe I'll go back next week and ask them then.
theoldnunshead.co.uk
2011 update - Old Nun's Head not doing jazz on a Sunday anymore, but still thriving. I haven't yet found out who the two musicians are.
2014 - five years later - pub still there, jazz still not there, folk music is there, still don't know who the musicians were.