I recall reading of a covert research station during WW2 (MoD 1 IIRC), looking into less orthodox weapons.
One of the scientists discovered that the ideal timing device for one of their underwater mines was aniseed balls (a type of sweet, for those who don't remember them), thus, as sweets were rationed, a special ration was arranged, however to keep the 'timers' dry until use some sort of cover was needed and condoms fitted the bill, so a supply was arranged through a local chemist(Pharmasist); neither of the suppliers was allowed to know the reason for the bulk orders and the members of the station gained a reputation as sweet toothed sexual athletes (and apparently, aniseed balls were suspected locally as an aphrodisiac).

Mr Red,

I believe you will find that the French eqivalent of 'French Letter' is 'Capote Anglaise' (English Greatcoat).

Walrus