I forgot to mention above that I did phone each of the airlines 24 hours before. US airlines simply quoted the party line regarding normal hand luggage which kinda put me off but when I got to check-in it was no problemo.
BA gave me an "Oh really...." (as in "that's interesting!") and as if to confirm this, at check in and at all gates they were totally ho-hum about everything.
Anyway, good lugging wherever you may go.
Craptone