Martin,
I started mine for the first time this week. Mine was a bit complicated as I have bought an unmapped MBE 9A4 and most of my problems were around the start map being far too weak. I did also have a pin pushed out of the back of a connector installed by Caterham.
My guess for your problem is either the cam or crank sensor not connected or working correctly. If everything else is connected I can't see what it could be. All of the conectors are unique. You could measure the voltage on the coil white/purple wire to ground this should be connected to 12v via the ignition relay and fuse B (15A) I think.
While you are investigating yours could you do me a favor and measure the voltage at ambient garage temperatrure across the ecu temo sender installed towards the back of the engine above the exhaut header. I have an issue there still on mine.
Also, have you had any issues with the indicators and hazzards. Mine don't work and Caterham think it is the dash control module circuit board hidden behind the dash needs reprogramming.