All lakes,well most that hold good fish are over fished.
There is a small lake called Barton court in kintbury,near hungerford,berkshire that produces fish often over the 20lb mark Plus, hungerford canal has fish up tp 30lb..
Also produces good bags of roach,dace,bream and perch.
any interest fishing the canal,get a permit,either day or a season ticket as i will be asking for them