A few days back this small beetle flew in through our kitchen window. It is probably a male spider beetle, a Ptinus sp (Coleoptera: Anobiidae).
Spider beetles are so-called because, with their long antennae looking like extra legs, they were thought to resemble small spiders. There are 8 UK species of Ptinus listed at the NBN Gateway: dubius, fur, lichenum, palliatus, pusillus, sexpunctatus, pubpillosus and tectus. The white patches on the wing cases on my specimen look like those for sexpunctatus but the background colour doesn't look right so I won't claim that as an identification. It is probably a male because in Ptinus the females have a distinctly rounder and less elongated body shape than the males (see here).
Photos taken in Reading, UK, on 2012-01-20.