Right, question time?

What type of spider is this that graced my presence this evening?
Its arse was as big as my thumb!

I'm just intrigued, is it actually from the UK?


Update: INterestingly the pattern on its back is very similar if not the same as that of the shell of the spider tortoise which is indigenous to Madagascar. I have to wonder if the tortoise was named after the spider, in which case is this spider from Madagascar?