About a week ago I had the same problem, battery appeared in good order, but no start just clicking. This was the first time I have had this problem. I used a portable booster pack and it started first time.
I had assumed it was the battery, but now I note from "GMC N's" post, it may be the terminal. I am assuming by using the booster pack, I bypassed the normal connections by using the positive terminal at the front of the engine and the chassis for negative.
I have enquired with RTCC about fitting a new starter motor, if needed it is a big and difficult job, 6 hours labour. Further, having discussed it with Gajet, he has just had a new uprated starter fitted, this is a big job.
