BEA airtours callsign was Kilo Tango or BEETOURS. Flt # were KT000 etc. Even when on lease acft still held G reg., confused some folks when a G reg 70 arrived in SyrianAir livery
I think I know as I was there from the start of ops in 1970
PS: airtours was always a lower case
a to avoid confusion with the tour operator Airtours up north !