AA turned up after just 30 mins, and asked me to turn it over, which I did. I couldn't hear the engine (noisy road) but he said it sounds like something is broken, and it's not a quick fix. His comment on the form is "Engine U/S"
Had it towed to Apple MG in Meopham. They were really busy and only managed to look at it late on in the day....they say it doesn't sound right when cranking, so they are going to do a compression test tomorrow. Doesn't look good. At least I have the AA Breakdown Repair Cover, so the first £500 of any repair is covered.
Fingers crossed it's not time for a new engine...
2004 MG ZT+ CDTi 135