Strange starting problem...........HELP

[busta]

This might seem strange, but I am really in need of some help.........Here goes

I have a 54 plate Lwb semi high top 135ps 6 speed 3.5t transit rwd.
The problem I'm suffering from is. The glow plug light flashes and the van will turn over but fails to start.

This morning I went out to go to work and the glow plug light just flashed and the van failed to start. I made arrangements with the local Ford dealership to take it in. I arranged for a mate to tow me there. When we turned up at the garage a mechanic came over, And I tried to explain what the problem was.
He jumped in and turned the key.........And it bloody started. We turned it off and restarted again for about 20 minutes, I had a cup of tea and it started. So I brought the van home, On the drive way I tried it again, but alas it failed to start again. I towed it up the drive (3 mtrs) and have a quess what.........Yep it started again. but now will not start again.
When the van is running, It fly's does not miss a beat. Don't laugh, my girlfriend suggested that it might be the Crank shaft censor. Do you think that could be the case??
It has done this before about 2 months ago. It went in to Fords they could not find anything wrong, because it started.

Please please Help, Nick

[ake]

If the glowplug light was flashing then it should have stored some fault codes. Get them read