regarding david Fedman's question about the mounting of the front brake on this Hirondelle, behind the crown, Craig Sandvik 's answer is along the right lines.
The action of the front wheel when revolving in a forwardly direction is just the same as that of the rear wheel. We have all seen what happens to the stirrup arms of, say, a Weinmann 730, when the adjsting nuts are not properly set up. The stirrups move towards the seat-stays which in turn stop any further movement thereby reducing the torsion on the arms and the brake bolt, preventing, hopefully a broken brake. This case applies with the rear-of-crown-mounted front brake. What makes it a little more difficult on the Hirondelles is the fact that the brakes are centre-pulls... or they certainly are on my model" Course". The cable arrangements are quite natty and the brakes work fine. The stirrups are, like many of the late 40/early50 period, pressed out of steel strip.
In the 80/90s I built a lot of time-trial frames with the front brake in this position... the Dia-Compe "aero" 400 brake with its cable entering quite diagonally was very suited to this position. Around about the same time there was a fashion in England among some builders for putting the rear brake under the chainstay bridge "... its more aerodynamic!!!" Apart from the crud that accumulated there.. there was always the forward and downward force from the wheel wanting to just brake the pivot bolt in two.
Similarly was it GT or Muddy Fox who introduced a special type of rear cantilever that was screwed on to pivots underneath the chainstays? Could never understand it.
Norris Lockley.. settle..UK