Hi Stephen,

We're not sure you mean double declutching in the traditional sense, as that's a technique used to change between different gears, usually for gearboxes without synchromesh (i.e. old ones!). Reverse gear rarely ever has or needs synchromesh in a car. If you are having difficulty getting your MINI's gearbox into reverse I'd suspect that there is an issue. It could be the clutch or gearbox, but it could also be the linkage, which should be less costly to fix.

Best thing you can do is bring the car to a good mechanic to have a look.