I've recently heard from Lawrence and I'm pleased to report the news is all good

The engine is in, running and the car has a new MOT
I was hoping he'd have posted by now as he did do a magnificent job of doing a full engine transplant from a Xantia into a 406. Not as simple as it sounds as there are some detail differences.
scottishpaul wrote:can u tell what which wire does the makes the solenoid work i need to try this with my car and would i still have to remove imobiliser from the pump first ?
Paul, there are two wires that will do the job. If you use a voltmeter, you should find one of the wires going to the immobiliser module (the black connector) has a suitable switched live via the double injection relay. Failing that you can also use the switched live that feeds the timing servo actuator but be careful which wire you use. Best to see which is live with the actuator disconnected. I think that's the brown plug but I'm not 100% sure. In any case, it's not the plug that goes to the pot on top of the pump with three wires which will be the blue one.
Good luck with de-armouring. Lawrence has the job off to a tee now and he has done it in-situ, as has Citronut. A PM to both may be in order if you need any tips/advice.