For posterity, here is the elusive Breitling Premier ref.: 777 of the Belgian Air Force. It was issued in 1951 along with the Pontiac chronograph and probably shares the numbering.
The Breitling F.A茅 chronograph ref.: 777 is different from the civilian version and might be a special order. It is 37,4 mm. in diameter instead of 38 mm., the writings on the case back are different with the reference being written inside and the technical datas being written in a circle, the lugs have no holes, are 19 mm. instead of 20 mm. and finally the dial and hands are unique to this watch with smaller counters and no tachym猫tre scale.