Hello Simon. That was probably me,I had a Lotus Elan following me before I turned off towards Polhill,although my car is bronzy black in colour. Still good to see my second Elan of the day enjoying the winter sunshine (even if I didn't give you a wave !!!)
Had it resprayed last December, was standard Moonraker Black, had the colour changed to Alfa Romeo Etna Black. As far as I'm aware it's unique to an S Series, although there is a modded Chimaera with the same colour.