This very small spider bit a lady in her home in Mid-Wales, and she required hospital treatment. I haven't been able to find it on the page for British venomous spiders and would be interested to know what it is.
There are further photos on: http://www.flickr.com/photos/flowtik/sets/72157636784010154/
I believe so. She felt it bite her and brushed it off. Shortly afterwards she suffered a fairly severe local reaction centered around the area where she had felt the spider. The spider was alive when caught, but died shortly afterwards so it seems likely that it was the one that she injured rather than a random spider that happened to be on the floor.