Spoke to the garage this morning and can report the following:
The problem vehicle was tested without the EGR vacuum pipe connected. Initially it was reconnected and made no difference to the problem and after inspecting the EGR valve, the vacuum pipe was again disconnected before my arrival. The sample vehicle was also tested by me with the vacuum pipe to the EGR disconnected. So in essence, the figures I provided for both vehicles were with the EGR vacuum pipe disconnected utilising the same known good MAF. Sorry for the mis-information. I assumed that both EGR vacuum pipes were connected.
The depression valve on the rocker cover was inspected prior to my arrival and found to be clear.
Incidentally, because the catalytic converter has been removed, the turbo could be heard through the exhaust system when the engine was revved.
Regards
Pete M