Just been in the garage to check things out. The two connectors at the back of the dizzy are definitely in their correct location. The TPS reads 4.94 volts between pins 17 and 30 at the ECU at idle when ignition is on and drops to 0.38 when on full throttle.
I tried to adjust the TPS to see if it made any difference - the idle just goes higher when I do.

Dave, the chap who looked at the car took a good look at the map sensor pipe and cleaned it. I suppose I could try and replace it just in case.

When the car was warming up the idle is about right, there is a definite and immediate increase when the car is warm. Switch off and back on when warm, jumps straight to high idle.