for years i fished claydon lake with 2.5lbs rods and 12lbs line. at that time the fish ran to around 35lbs and i hooked and landed them to 26lbs on this tackle.
i now use 3.5lbs diawa dictators with emblem big pits filled with 18lbs gr60 line. if im using pellet or boilly then ill use a 30lbs braid hook link and for live/dead baits ill use 80lbs braid as hook link.
It is interesting that you mention Claydon Lake as that is one of the English waters that was originally stocked with wels by Lord Rothschild many years ago. Rothschild owned the Tring Group of reservoirs and he introduced the fish to Marsworth Reservoir, the middle lake at Claydon and the Shoulder of Mutton Lake at Woburn.
Cats were showing at Claydon in the fifties and Reg Hutt caught one which, I believe, weighed 26lbs and was accepted as the British Record cat.
Until about 1963, fishing was not allowed at Woburn Abbey, but then tickets were made available and both cats and zander were caught. I believe that some of the cats found their way into other waters, as did some of the zander.
The cats in Marsworth have rarely shown since their introduction, though one that weighed 44lbs was caught from Wilstone Reservoir (one of the Tring Group) which, I believe is connected to the other reservoirs in the group. The last time I visited Marsworth Reservoir was in 2004 and Bernard Double told me that a couple of about six ounces had been caught shortly before my visit, so it would appear that not only are they still in the water, but breeding too.
A stream runs through the lakes on the Claydon Estate and eventually joins the Great Ouse, though I forget just how and where, and it was suspected for many years that the cats had made their way into the river. Certainly, several anglers, Trev Kilby and I included, hooked fish that were far too powerful for the tackle we were using for much lighter fish and we were comprehensively smashed. Trev and I hooked our fish at Lavendon Mill Farm, just a little upstream of Harold where a nice sized cat was caught a few years ago.
Although a number of Home Counties catfish did originate from those in the Shoulder of Mutton, it is common knowledge that many were transported from the continent to British waters illegally. Thankfully, the illegal stocking doesn't seem to have had any adverse effects and the cats don't seem to bother those who don't want to catch them. However, zander have also been moved illegally and the same cannot be said for them. There are many who feel that both the legal and legal stockings of zander have been disasters.
