So I bypassed the filter and hooked up an inline pump with no change to the car at all so the filter can be ruled out now.
I changed the MAP sensor today with a known working one and again no change.
The turbo actuator had been tested and was found to be in full working order.
I'm think at this stage the only thing left is to remove and test/replace the injectors or swap ECU's and recode to allow NATS to function

Both scenario's don't thrill me but are better than changing a fuel pump.........