Its called "French Polish" finnish and was very popular back then with high end cars.

 

In the UK, French polishing is usually applying shellac dissolved in meths (is that denatured alcohol?) with a pad. The French polisher (he doesn't have to be a French national - there's a British guy who does it on TV) keeps rubbing it in over several coats to achieve a very nice gloss. It's the traditional finish for quality furniture from late Georgian times on into the 20th century. It's not as resistant as more modern methods, but is way easier to repair and to many eyes looks better.

I keep reading about how various owners have restored their wood. There seems to be a lot of different possibilities and I've still no idea which I'll follow ... if I ever reach that stage.