Firstly thanks to all who helped me diagnose that the plugs were not the problem with my wifes car.
This car will not start and idle. It will start first time, but then stalls. It wont stay running unless it has a good helping of throttle. It then belches out wedges of white smoke. Then it will idle. Then it runs perfectly. No MPG problems, or anything. No fault codes. Perfect.
1. Glow plugs have been checked and are working
2. Starter motor was changed so that it started first time, (half the original problem cured)
3. EGR valve checked and is working properly ( May well blank it off after looking at other threads anyway)
4. All of the induction system checked and is leak free.
The next step seems to be going to a garage. Luckily I am not far from a diesel injection specialist that is an agent for all of the major fuel injection manufacturers and was thinking of going there rather than a Ford dealership.
Unless anyone has any other ideas? I think I have remembered everything I've checked anyway. I've been so long trying to figure this one out , may have forgotten something. LOL