Re: Overheat (no seriously!)
Right - My view from your really helpful replies is that whatever it is, it would be likely that the garage who did the service should either have picked up on a dodgy radiator, or they screwed up with the fluid top up. Either way, I'll pop down there (armed with my new found knowledge!) and get them to have a second look at it.
The service was steep, so they should not have any issues with me making sure it is all above board. The cost was high as they did replace the 'sump plug, the brake hoses and a headlight fitting' (they said it was directing the wrong way!! - it's never been changed, so I think I may have a word with them over that too, as it does sound as likely an explanation as a teapot maker saying '....well, I didn't know chocolate would melt...')
Anyway - keep 'em peeled as I'll come back with the next instalment soon (this is almost turning into a blog!)
Thanks again, people - I truly have found the worlds most helpful and friendly forum.