Actually Bs had the bench type seat as seen in these pictures. There were aftermarked pan seats that were put on alot of machines. Later A-Cs such as the D270 had pan seats from the factory.
The one with the mower interests me, this tractor we would refer as a wartime moded in the US. It has the extened air cleaner stack and wide fenders for steel wheels as well as the hole in the clutch housing for the starter but not battery or electric start. I did not know any of these were sold in the UK. The front wheels and hubs are like nothing I have seen before.
Thanks for posting!