I've received an email back from the British Arachnological Society.....They believe it to be an adult male Pseudeuophrys lanigera. I was surprised that it was a fully grown specimen as it was so small. Here's their page on the spider - srs.britishspiders.org.uk/portal.php/p/Summary/s/Pseudeuophrys+lanigera
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Mon 20 Feb 2012, 16:17,
archived)