The saying about welshing on a bet does piss us off.
I'm Welsh, from Swansea, South Wales and have more English relations through my sisters' marriages (I have 3 of them) than Welsh. In fact I know more Yorkshire people than Swansea people, Yorkshire and South Wales tend to have the same sense of humour.
Prejudice wise I would say there are more narrow minded knobheads in Wales than there are in England. "As long as we beat England nothing else matters" Pillocks!
Saw written on a pub wall in Greenock, Scotland:
The Scots provide the verse
The Irish provide the tune
The Welsh provide the voice
The English provide the audience

Dick, haven't seen for a while. Hopefully soon but not this weekend.

Mike