Hi,
I would be inclined to agree with Awemawson. The Wilkinson Sword safety razor had a hollow curved top that had a screw that passed through the blade and threaded into the handle via a curved support. They were part of the standard 1st WW issue army kit. The kit also contained a glass hone so the blade could be sharpened. You could still buy packets of 5 blades from barbers and chemist shops at least up to the 60 or 70s. They came in cardboard packets, each blade wrapped in paper.