This is the Sigma 17-35mm f2.8-4.0 EX DG wide angle lens for Canon digital cameras. Nearest price is £260-300 but Jessops are doing it for £135. Just picked mine up. It beats the kit lens hands down.
EX lens, so 3 yerar Sigma Warranty
HSM focusing, fast and quiet.
F2.8-4 means it will have decent low light capacity.
On a 1.6 Crop body it will be the equivalent of 27-56mm
Is a DG lens, so can be used on Full frame cameras as an UWA lens on the 5D, Canon film cameras, etc.
By the way, the Jessops image shows a Mk 1 lens - It is actually the Mk II lens they are selling, which is the improved one.