I didn't make it to Goodwood as my poor starting problem progressed to an only starting with a bump start problem Its OK at home - we have a steep drive - but no so good if I was parked on level ground at the circuit. I think I've traced the problem to a poor positive connection to the starter.
I did get to the South Hants Vehicle Preservation Society event at QE Park in the other car where I picked up a new starter for £10 (I didn't have the heart to haggle). I fitted it this afternoon and went for a drive. Then I googled the parts to repair the connection on the old starter, which are available for £9.99, so the incremental cost of my drive through the South Downs was 1p - money well spent!
Mark