Stu,
When I lived there I caught a few carp and tench around Maidenhead and around Wraysbury. I never caught any bream, how things change. I caught chub to 5lb 2oz, roach to 2lb 4oz and barbel to 9lb 12oz. These were all very good fish in those days. There were loads of roach and chub around and a fair number of barbel. I wonder if the bream weren't around then. I fished around Windsor and Marlow and never saw any. As you say the floods probably shoaled them up but I think the odd one would have been caught if they had been around then. The Jubilee river sounds great. I wish it had been around when I lived there. I hope the local anglers get a lot of pleasure from it.