As much as I hate to do it it looks as though I'm going to have to break this car and sell the bits.
The missing transmission is specific to this model only and nobody has one on offer anywhere I can find, used or even faulty.
It's an Aisin Warner 6 speed with serial number 20 GK01 0036181 Citroen part number new 2222.ZS, or exchange part 2232.K5, if anyone can point me to one that's affordable I might save the car yet.
I've popped a battery on it and everything that can be tested works, can't start it because the starter motor needs the bell housing to bolt to.
Mileage is 70106 so the engine should be good, hardly run in on one of these.
Anyone who has never made a mistake has never tried anything new. (Albert Einstein)