Well.... crap. The UK is a temperate country, so it's too hot for lions and too cold for polar bears, and all the nasties in between. Well, until now. Poisonous spiders are running rampant in the UK, causing serious damage. One man nearly lost a leg because of one bite.
The spider in question is the 'false widow spider'.
WARNING - Graphic content, do NOT open the first link if you don't want to see a nasty wound.
http://www.dailymail.co.uk/news/article-2453833/Decorator-nearly-loses-leg-bite-UKs-poisonous-spider.html
http://www.itv.com/news/story/2013-10-11/false-widow-spider-rise-in-uk/