Canoehead: "Break Break" is quite common on French ATC frequencies, although it is not often heard in other parts of Europe (the exception being very busy frequencies around LHR/LGW/AMS etc).
FrenchATCO: Thank you for your reply, very interesting. I would be much happier if the callsign was used before the Break Break, because if it isn't I have no idea that my call has been heard or understood. This could cause me to call again causing confusion and blocking the frequency when there is no need to do so. In my mind, you could just as well have said "break break" to another aircraft which happened to transmit at the same time.