A friend in Paris sent me some photos of a rusty 1940's 650B randonneur frame. It has a center-pull brake mounted on brake bosses on the fork, and no brake bosses on the back. The brake bridge, on the seat stays, is drilled vertically, probably for a fender mount only.
It looks as if the frame was designed for a rear drum brake as it has a braze-on loop on the underside of the left chainstay (to hold the arm on a drum brake?).
Were drum brakes common on high end touring bikes back then? Who made them besides Maxi-Car? Were they wider than standard hubs? Did any maker or constructeur use such hubs regularly? Am I missing something?