Posture curve
The log carried an advertisement in the 70s. I bought one and it helped considerably as the Trident had seats made by teleflex who do the boating cables. Had a couple of the designers in the cockpit "deliberately designed as hard and uncomfortable per request by BEA's chief pilot as he didn't want his pilots falling asleep". The VC10 was a different kettle of fish. Good luck a chiropractor sorted me out permanently in the end.