Well, time to move on then after the tea cosies!
I decided to back track in WW1 and look at the origins of the tracked vehicle.
The War department, often through the RNAS, did quite a lot of trials and assessed a number of different tracked vehicles. The problem being that most were based on agricultural machinery. They were not really suitable for trench crossing.
So one of the machines brought over from the USA was the Killen-Straits tractor.
This was a tracked vehicle produced in the USA by the Killen Walsh Manufacturing Company (the name was changed to Killen Strait in 1914). The company were based in Appleton, Wisconsin. This was intended as an agricultural tractor.
It had 3 sets of tracks, two at the rear powered by a Waukesha engine with Remy ignition. The front track was not powered but was pivoted for steering. 2 models were produced, the 30-50 and the 15-30, the numbers presumably refer to the horsepower available. The engine was of the 4 cylinder petrol type with a closed cooling system. The engine was in the middle of the chassis and drove the rear tracks. Waukesha produced large reciprocating engines.
The tractors were imported into this country by the Vulcan Car Agency; the prices seem to be around the £500 mark.
The tractors had been in production since 1910.
At least one was brought over and tested by the RNAS as to its viability as a tracked vehicle, judging by the photographs it seems to have been a very lively machine to drive. One was fitted with a Delaunay-Belleville armoured car body, and as such may have been the first armoured tracked vehicle. It appears to have become a dead end due to its limited trench crossing capabilities.
I found some plans in one of the MAFVA magazines in 4mm to one foot scale and enlarged this to 9.53mm to the foot (1/32nd). Searches on line produced more information and diagrams of the tracks, chassis and drive.
I will start with the chassis, this is built from I girder channel chopped up and cemented together with Salters MEK, I strengthened the joints with superglue. The front curved section is from plastic card and strip. The patent pans show the position of cross beams and the bars between the chassis members.