I am sure that if I was expecting to land at Luton and got told "vectors down wind RH for 23" I would soon sus it and a gentle reminder that I am for the other field.
Buzz use to manage with alpha numerics, only the CDG had numbers, ie "Ukay 272". We had a nice card that had all the flight numbers on it and next to them the relevant callsign.
When was a Fighter Controller in the RN I sat down in my seat onboard one of Her Majesty's destroyers, to be informed by the Chief Ops Radar that our callsign for the day was Sierra Zero Zulu (have a go people - sit there and try saying Sierra Zero Zulu in a hurried fashion like what you have to when you say "localiser from the right, descend with ILS, 160 til four, 123.8... whilst adjusting the speed bug. selecting flap 5 and identing the ILS....." . After about 15 minutes of tongue twisting gymnastics the aircraft suggested I adopt the callsign "Zulu" which I duly did, cue much banter from the rest of the Ops room about "dont point that chinagraph at me" etc etc!!!!