I do a fair bit of email marketing to UK businesses and recently came across a company called Customlists.net - not going to post their actual URL as a link as not wanting to promote their business.
BE VERY CAREFUL and DO NOT BUY from them - their data is a load of rubbish, they claim to have UK Business Data but when you receive the database its absolutely made up, basically they have taken a computer generated list of first names and surnames and then spidered out for a list of websites then combined the two and the result is a ton of garbage WHICH THEY ARE SELLING!!! They then give you a gaurantee that they will give you more data if you have a large percentage of bounced emails - well 50% of it goes though and probably just ends up in black holes or is redirected to actual recipients (but in the case of UK data having checked the authenticity most of the .com companies in there are in the USA) and the other half bounces - what a pile of crap, this company should be banned - trouble is they look legit because they are right at the top of google and take paypal payment plus give you loads of good feeback.
Be careful everyone and dig a little below the surface! Remember if its that cheap then it must be too good to be true - and this is definately on of those scams!