Turns out you just use pliers to pull the white bit out of the grey. The pins then push out.
The connector is genuine rover from an 97 MPI. The connector on the other end just looks like the other half of this grey connector, and is mounted just behind the headlights, the side closest to the engine.
I spent ages looking online, and i believe the pins are called Dupont. They usually wrap straight around the wire, but these are wrapped around bullet connectors.
None of the replacement wiring looms have these pins, so despite my best efforts to buy plug and play, this will need some work. Im just not sure if the best way is to buy the Dupont set. I would like to use the original connectors.