Many thanks for the TD18 pics, Ron. My Father drove one on a farm over here from 1952 to 1991. It was like Paddy's brush, new handle, new head but the same brush. In Dad's case, new tracks, rollers, engine (upgraded to 18A engine in 1967), clutches, gearbox but still the same tractor.
The farm had three at one time, two ex army, one (Dad's) bought by the British government for the groundnut scheme in Tanzania. I put some time in the seat ploughing under Dad's supervision when I as 16. Those steering clutch levers!!!! My oh My. Dad put in regular 12 hour days from harvest right through to spring. Didn't do him too much harm, he lasted until five weeks ago, just short of his 84th birthday. Mind you he was bloody near deaf. Straight through exhausts, it sounded like a Lancaster bomber on take-off roll from half a mile away.