Well I whipped the starter motor out and took it to the auto electrician.
He tested it and reckons it is fine (a little noisy though).
He seems to think the voltage coming to the starter might be low.
He wouldnt tell me any more than that. I think he wanted to get some money out of me for further info. The hide of him!
What would cause the low voltage?
The only 2 things it could be would be the relay or the immobiliser. As far as I understand, they are both essentially just "on/off switches". I wouldnt have thought these would be the problem.
Can any of you guys shed some light on it?