I think there will be some kind of braking system to the tracks to aid steering. Ie. Turn left and left track brakes. Just guessing mind.
I wonder if my friend with the Ransomes will know. He used to own Gretna peat moss.
Nice Series 1 but a chassis up rebuild. Tidy looking mini pickup behind it as well.
BTW. Does The Showman by you lads a pint every time you take his photo?