hello mate,
just done battle with it again, and it's won, again. I pulled the motor off and tested it, it turns out that it spins up when i bridge the power over the main threaded terminal and a small spade connector, rather than the smaller threaded terminal as I drew in the diagram above.
So on the floor next to the car i can get the starter working, but then i shoved it onto the engine and turned the key and there was nothing.
To fill me in on a bit of the theory behind it, is the ignition switch providing a live or an earth? It certainly seems that in order for it to work as i have it set up now the ignition switch will need to be live to make the motor work.
If that is live, i think i'll have to start playing with the voltmeter thing, although i've never really understood it :S