My relay has arrived now too, so next thing to do is get this back to the Porsche service center and see if the car starts.
I do have a question though as I have been re-reading Adrian Streather's 993 book and in the Alarm, Immobilizer and intergrated central locking system section he states if the anti-drive-off feature is activated when the alarm system is armed the ignition and injection systems are disabled. He also notes that when relay 61 is disabled no power is available to the starter motor solenoid.
I am a bit worried about that statement as I have always been able to crank the engine, so it might be I am not actually going to solve the problem. Is there ever a state where the immobilizer could prevent starting and still allow the starter to turn the engine over?