I am assuming it is unlocked but I have found the following:
Launched in October 1935, the Tug was a three wheeled ‘mechanical horse’, approved and marketed by the Ford Motor Company, and designed and built at County Commercial Cars Ltd., Fleet, Hampshire, using Model “Y” engines and ancillaries and body parts from Dagenham (Briggs body number 161/---). Available as a tractor with or without a two or four wheeled trailer. Not a successful venture; only 111 vehicles were manufactured, although 121 bodies were made by Briggs. County Commercial Cars also marketed a three-wheeled van based on a similar design called the ‘Devon’, the Tug having originally been called the ‘Dorset’ by the company.
All of which appears to make Mr. Hondast correct.