As crazy as it seems I'm fairly sure the position of the drivers seat has something to do with this.
I have tested re setting the fault several times with the seat forward. (Where my wife sits) and it doesn't work. Then I slide the seat back, reset it once and it fires up straight away.
I have done this test a few times with the same result every time.
Doesn't make any sense at all but that's what happens.
Now I need to investigate what wiring is under the seat that could cause this.
Time to rip the interior out I guess.