Pinched from somewhere else on the web!
"If it's not the fuel pump relay as others have suggested, then try cleaning the crankshaft sensor - it's held in by a
10mm bolt at the end of the engine block (forget which end, but it's got a thick-ish wire to it). Undo the bolt, pull
it out, and the chances are it'll be quite dirty - a brown/black colour (as a result of carbon deposits at a guess) -
get some emery paper and clean it up so it's a nice shiny silvery colour, put it back in, and watch the starting improve
tremendously.
I did this on my Carlton when it refused to go at all, after having tried new plugs, leads dizzy cap, rotor arm, king
lead, coil, another coil (in case that one was duff), and cleaning the crank sensor cured the problem straight away."
This was for a 2.0l carlton so the crank sensor is in a slightly different place. Front of engine right had side I think just above the toothed wheel. When putting it back make sure the distance is exactly as it was before you took it off.