Thanks for all the input. Where should I go (online or on-street) for second hand lenses/equipment?
I currently have that lens for sale and it is not yet 3 months old. It will come with the remainder of the warranty with it. I bought it from Mifsuds. There is a genuine reason for sale which is because I now have the 5D MKII which came with the lens as a standard fit so I have a spare 24-105l F4 IS USM. it really is a great lens see the links to read a review. Pm me if interested, By the way I am asking £700, despite the current RRP being £849