Jessops World Camera Centre in Birmingham. I decided to buy the Sigma 18-55mm f/2.8 and asked the staff for a bit of advice first. He actually told me to come back with some reference prices from the web (without prompting) and they'd see what they would do. In the end, they got within £10 of the best internet price I found, and threw in a £21 UV filter for an extra fiver. Nice work fellas!