Peter, originally there was an ignition without ballast resistor in the Morgans of "our" vintage and that is what I have in my car. The square thing seems to be such a resistor in yours. The wire goes from the ignition lock to the resistor and then to the coil.
Perhaps your coil came with the electronic ignition from Mobelec (I'm surprised that they shouldn't be around anymore). If so, you should stick to a coil with resistor. Otherwise you can change to one without. The resistor is only there to help produce a strong(er) spark when starting the engine (with weak battery or in the cold).
Frank
