Thanks Andy,
That's something I did not know. If I had read your earlier posting I would have realised. It is interesting that two cars that were originally four seat Plus Fours were competing in the 2018 Classic. Also I always think it a bit odd that serious racers use four seat Plus Fours - though I am sure you will remember That in the 70's Gip Shaw used to sprint his quite a bit.
Quentin