After approx 1982-84 Minis used a system where by they used a 9v coil which was fed from a ballast resister in the wiring loom and a feed from the starter solenoid when starting the 9v coil was fed 12v for better starting.
This system is renowned for the balast resister which feeds the White/Pink wire to the coil + of overheating and the ballast resister burning the wiring loom out in the engine bay and usually approx 6-8inches from the fusebox on the right of the car.
If you have a ballasted system on your car I strongly advise you to convert it to standard 12v system.
Parts you will need are
New 12v 3.5ohmn coil available from Minispares GCL 216 or sports MSC105 or the Lucas Sports Coil DLB 105
Cable and connectors for a new 12v feed
Fuse one is the normal switched supply from the coil, make a new white feed wire ( SWG 12/14) and connect to fuse one where the original white fed the resister white/pink
Tape the new feed into the loom or attach external and run to the new 12v coil you've fitted, connect up the - coil terminal as before, discard the White/Pink & White/Yellow previously connected to the old coils + terminal and connect the new white 12v feed to your new coils +
Your now running a standard 12v Ignition System and wont have a nasty surprises with smoke pouring out the engine loom and half a days rewiring.
If You Have A Ballast Ignition This Is One Modification You Need To Do