Forget the reports about 200Ib Carp, they are a different species....as I mentioned before the official world record for the Carp we know is just over 82Ib (forget the exact latin name but you know the ones I mean) I also saw recently a picture of a 90Ib+ Mirror I think in Carp talk that really did look that size, but it was not caught on rod and line.
I am not sure I agree with Steves comment about big imported fish losing weight?. look at Darenth and Ringstead. I think a rich bolie diet can make up for the lower temperature climate.
How about this...some of you may be surprised to know that there is actually a 70 pound plus "Carp" already living in the UK....its in Hawkhurst specimen lake down in the south east...but before you start going all wobbly and getting your maps out to plan your trip, I should point out its a Chinese blue Carp. There are/where two of them in there and although the smaller one I think has been caught a few times as far as I am aware the big one (stocked at 74Ib) has never been caught, even though it is seen from time to time...quite an achievement in a small lake fished by some of the top guys in the country. The fact that Blue Carp I believe are mainly filter feeders might have something to do with it but as I say the smaller one has been caught on a hook so it can happen.