Latest info, ran around the country lanes last night in the vain hope of getting some charge into the battery. Checked it this morning before starting it, 10.45 volts, still started fine. I have the full service history from new, so, checked through it all and there is no record of a battery being fitted. As I thought it is the original battery from 2007.
Visited Lexus, Newcastle today and have arranged to have a new battery fitted tomorrow. Price? They said £84 + free fitting, can't get any better service than that. 😀