The Mini came over the years with different brake system layouts. They are listed here as they progressed in time. Though not all of the layouts were used in the export models. First came the basic Single Line system using a master with only one internal piston. With the single line serving all the wheels with the brake proportioning valve being used to reduce the line pressure to the rear brakes.

The next system moved to a Double Line with a master cylinder with two separate outlets with one serving the front brakes the other the rear. The front and rear lines had the same line pressure. The brake differential switch was only to sense a difference in pressure between the front and rear system and its sole purpose was to trigger a warning light on the dash. When used with disc brakes the brake proportioning was redundent. Though I think it was still fitted with the drum brakes.

The next is really the same but with Diagonal Lines instead of the lines going to front and rear. The left front and right rear were connected and the right front and left rear. The thinking was that as 60% or more of the braking is done by the front brakes if a pressure loss was experianced in one line then at least the one front brake was still working.

The final layout is the same but with a brake pressure Differential Switch fitted. This diagonal system does make it a bit difficult to reduce the line pressure to the rear wheels so I think this was used only with a disc brakes fitted.

There was a direct acting Servo or Booster fitted to the Brake Master from 1988 on. Before that I believe, if memory serves a Single line servo was fitted to the early "S" and the Works rally cars.