just been reading Laurdan's post and it reminded me: someone on our site found this trapped in her courgette netting recently and called the RSPCA to come and rescue it.
she wasn't 100% certain that it was a grass snake and thought it might be an escaped exotic poisonous number so thought it better to be safe than sorry.
the RSPCA said that because they're a protected species it couldn't be moved away from where it was found, only released and it's now living quite happily on her plot, merrily making holes in the ground in amongst the rows of veg, and may even have eggs in her compost heap – very exciting!!!