Hundreds of Allis B's were imported in Britain in the 1940's and were well liked tractors. The US models featured fixed bow front axle, 3 forward gears, and normally a pan type seat {this one's seat has been changed} and fitted with after market adjustable front wheels.
Allis Chalmers had a large distribution depot in Southampton on the middle British southern coast. In 1949 they started to build a British version of the B with 4 forward gears, adjustable width front axle and the bench seat. A remote hydraulic cylinder to raise & lower implements was an option.
The engine was the standard AC kerosene 4 cylinder engine. Perkins offered a conversion kit to fit their 3 cylinder P3 diesel engine with electric starting. Many companies supplied mid mounted implements for row crop work.