Oh dear...

…that will need checking out. 

Contacted a local ‘automatic gearbox’ specialist and they can fit me in for a diagnostic in four weeks time at the end of October. The cost for this is £80, that’s just to plug it into a computer, who knows what any ‘real’ work will cost, I’m hoping its a faulty sensor! 

In all fairness the car is 15 years old, we’ve had it from new and it’s been exceptionally reliable and cheap on repairs. We still like the car and don’t want to part with it, but we’re at the point that we don’t really need two cars any more so I suspect it might go sooner rather than later.