Ordinary back-pedal brake (I think they are called) - the only kind of brake that was common on standard bikes until the 70's in Sweden I would think (I suppose they still are used on new bikes)
Thanks PerA. No, SJC1952, I don't think it is a fixed wheel. If it was, I don't think the back pedalling brake would operate. I have only seen one bike with a back pedalling brake and that belonged to a friend of mine when we were still about 10 years old in the 1950s The back pedalling brake was rare in the U.K even in the 1950s It is an amazing piece of engineering
The bike enthusiast should be able to tell what this kind of brake is called. By the way Hermes bikes were made by Nymans in Uppsala, Sweden, where my father lived at that time.