Thanks for the replies - interesting discussion. I've gone back on my negatives and I've found the strip of film where that picture comes from.

The strip has 4 negs on it, one from my home (no idea of the date) and 3 others:









so these pics were probably taken at about the same time. But because this is obviously pre-digital I have no way of dating this.

It's weird you mention Brands Hatch, as I have visited Brands on many occasions but the only pictures I have from that track are of the 1982 Transatlantic Trophy and I'm sure the they're not from there.

It's a mystery....