OK, mine isn't finished but you can get a rough idea of the colour from this. It will be Sea Green BS 381c 217 - inside and out.
It won't be to many people's taste but I want something period and, much as I love BRG, I wanted something a little different.
I read that small racing teams in the 50s would occasionally paint cars in whatever they could get their hands on (times were hard). BS 381c 217 is the green that was used by Southern (and some other) Railways on its buildings. I like to imagine that the paint was "borrowed" from a small hut on some sidings....which is more romantic than buying it online.