I can recall the Airtours flights using the callsign 'Beatours' operating wef mid 1970; I was stationed at the radar unit on the northside at Heathrow at the time operating as a 'radar monitor'.
I'm sure that in 1974, RAE acquired two of these ex BEA aircraft because I remember 3 Comets ariving at Farnborough in August, two of which were 4Bs and one of which was 4C XV814 but I don't remember the other registrations; the two 4Bs then went to Lasham where presumably they were broken up by Dan Air who operated 4Cs at the time which were maintained by Dan Air at Lasham.