Spent a bit more time trying to trace the strange electrical gremlins on TBE, symptoms are around the drivers seat not moving and a feint lights-on buzzer when ignition is off but key still in ignition.
The door switches look good on a meter, which makes me slightly suspicious of the alarm ecu, given the live data coming out of it. That doesn't explain why the seat eco is unresponsive when the seat doesn't work, so could be 2 separate issues, although they seem to play up at the same time....
I will have another poke around today... ...although I might just scrap it, as was planned anyway once she has to start going back into the office due to LPG availability.