If anyone's interested I worked out my earlier question a couple of days ago on a kangoo. If you disconnect one coil the ecu shuts down the driver to the other coil in the pair (ie 1+4 or 2+3) so if you disconnect one of the good coils the engine will try to run on one cylinder, if you disconnect the faulty coil or its pair the engine will run on two cylinders. (Probably bad practice though!)