Non-starter – 12v supply to rear starter relay

[Air Support]

I’ve traced my starting problem to a lack of a permanent 12v onto the front pin (pin 30) of the rear starter motor relay – if I bodge an independent 12v supply direct to this pin, the car starts perfectly.

So the question is – does anyone know where this 12v feed comes from? The build manual clearly states that the supply comes direct from the rear 80A maxi-fuse in both the wiring diagram and the table “routing and function chart (E03)”. Looking at the rear maxi-fuse, the reality suggests that there are only 2 cables to it – 1 from the battery and 1 from the alternator (?).
There is also a photo in the manual which contradicts the wiring diagram and table info and suggests that one of the 4 rear fuses supplies a feed to the start relay.

Anyone know the reality as to where this 12v supply should connect to please?
I think I’m missing an easy fix!

Thanks in anticipation.