Twenty odd years ago my son inlaw and I had sole access to 4 lakes (tench) and about 500 yds of The Tove which ran through the farm,we did on occasions fish for the chub
adopting a roving approach,and we did catch quite a few chub to about 3 lbs but it was not done seriously,we were more interested in Tench. We did see the odd fish or 2 which we thought might knock the 5 lb mark, which were big chub in those days. With out doubt over the last 10 yrs signal crayfish have become well established in the Gt.Ouse system which has provided a lot of fodder for all the larger species giving much bigger fish to date,if I remember correctly I'm sure
M.K.A.A. had some of the river at Castlethorpe.If you're in Bletchley anytime go to the tackle shop in Victoria street
ask for Brian he's a wealth of up to date local knowledge and a nice bloke with it
Happy days