I read sympathetically of your problems with our roadworthiness regulations, and perhaps my experiences with a J2 MG a few years ago will be of interest.
Taking the car for test purposes we tried the footbrake and pronounced it “ok”, while the handbrake (which is very long on this car) had amazing powers. Our tester possessed large boots (specially for stopping Austin Sevens) and with superhuman effort achieved 50% on the Ferodo brake meter. The handbrake gave an easy 70% and so the car passed.
However, the testers’ manual describes only primary and secondary braking systems. Either of these may be hand/footbrake, so in this case the handbrake should have been classed as the “primary”.
Most of those who MOT cars don’t ever think of that interpretation of the rules, so this is a sort of “let-out” for Morgan 3-Wheelers with hand-operated front brakes and for earlier Austin Sevens with hand-operated front brakes. The basic requirement is for the primary brake to achieve 50% and the secondary 25% efficiency, whichever they may be and one to act as parking brake.
[Name and address supplied. – Ed