The Belgium TNT operation used the call sign "Qualitay" as their three letter code was TAY.
I did some contract work for TNT with Channel Express (Channex) and we would be "Nitro" from STN to LGG and "Qualitay" from LGG to BGY or other European destinations.
"Channex" call sign used to be "Express Air" (As it used to be Express Air Transport), but this got confused with Air Europe Express so was changed.
Soon after the change, Air Europe went bust so the change was a waste of time.
I can't remember the Airwork call signs at Hurn in the '60s but I do recall the BAC 1-11 test flight call signs were "Lima 22" or another number, as each test pilot had his own number.