Don't worry, I'll try and remember to bring one in, but thanks anyway Matt.
Trouble is, on the few occasions I have done this before, having slipped back into usual automatic-commuter-zombie mode I have been known to leave my fiddle on the train. Fortunately due to a lot of luck and having some personal contacts with railway staff I have managed to retrieve them again, but I'm sure my luck will run out at some point.
Maybe I'll just stick to unaccomplished singing.

Sal