Pilot DAR a little annecdote; I was reading recently that Hawker Siddeley test pilot Duncan Simpson was asked to test fly the Strathallan Collection's Hurricane after a lengthy refurbishment. It had been acquired by the Battle of Britain film producers in 1968 from a Canadian who had being flying it. Simpson found its roll control absolutely appalling and quite frightening compared with the example he'd been displaying at airshows. The Shuttleworth Collection lent Strathallan the ailerons from their non-airworthy Hurricane and, lo and behold, Simpson landed after the next test flight wreathed in smiles.
It transpired the Canadian chap didn't have any ailerons so had built his own set from scratch and without reference to plans - and had added non-standard ground-adjustable trim tabs in an effort to improve its manners in the air; these had been discarded during the rebuild. An RAF pilot who flew the aircraft during the BoB film confirmed roll control had been diabolical even with the tabs in place. The design of the homebuilt ailerons didn't include vital aerodynamic wizardry employed by Sydney Camm's team; this led to them over-balancing - or something like that.
Sad to say the Hurricane returned to Canada and was destroyed in the Canadian Warplane Heritage's hangar fire a couple of decades ago.