www.firstcall-photographic.co.uk deliver the 5Lt sizes aswell.

It's a bit annoying Silverprint won't deliver these - they're so much closer to me than the W. Country (but Firstcall are v. good at next-day delivery)....but I'm too lazy to carry heavy bottles & anyway always end up buying too much other stuff aswell, and parking's impossible/ congestion charge/ traffic wardens moan moan :o