Spotting

Your pictures are dark, but I'm guessing cellar or shed. If so, that's perfect for these beneficial spiders. They eat only woodlice, and control that population. The BAS notes, "Woodlice Spiders are one of the very few British species that are capable of giving a painful bite," but the EOL says the pain from the bite is most likely mechanical - they have large fangs. They do not pose a health hazard.

http://eol.org/pages/1184230/overview