I was thinking a bit more about the second hand market and that if you did buy via a reputable dealer you'd at least have some guarantee. I guess I would be wary of buying second hand from a private seller.
I thought that Jessops dealt in second hand cameras, but unfortunately it appears that they don't any more.
Jessops axes used equipment service news - Amateur Photographer - news, camera reviews, lens reviews, camera equipment guides, photography courses, competitions, photography forums
You might find that your local independent camera shops do it, though. And if there was anything needing attention they'd most likely fix it before selling.