Indeed it is the Tenora Dyamic 40 so it's a point for PJ.
The Dynamic 60 (in which Jan Tenora was tragically killed) has featured here before but not this earlier version, the 40.
Sorry about the confusion over the engine, nicanary, but I had it as a 1-litre twin-cylinder, perhaps a bored out smaller one.
I would of course have answered 'yes' to your 750? question if I'd had the information PJ has now provided.