Paul S kindly provided me with photographs of this exquisite writing instrument. Though it has a Conway Stewart No 6 stub nib, I can find no indication that it was made by Conway Stewart. There is nothing on the combo to identify the manufacturer.
Moving the central gold-filled band exposes the nib, and the rear half of the body is turned to bring out the pencil. The gold-filled cap at the rear unscrews and holds spare leads.
The barrel is chased black hard rubber. Altogether it is a splendid exercise in design and engineering. Given its high quality and excellent finish, this combo may well have been made by one of the major manufacturers of mechanical pencils.