Ok, an update:
Tried the car using a spare 40mHz rec and trans, still the same issue, so that ruled out the radio gear.
Looked on google to try and hunt down a manual (didnt come in the box ) found a pdf here:
http://teamassociated.com/pdf/cars_a...esc_manual.pdf and the ESC is programmable




which I didnt know.
Downloaded and set it up again. I think Adam must have had the trigger pulled (or something) when I turned his car on, which must have knocked the throttle out of sync.
Live and learn I guess. Shame he had to miss out on 3 legs of his final, would have doubled his track time yesterday. Oh well. Onwards and upwards..... Going to set the ESC up in advanced functions for him now.