There was another novel dating to about 1970ish whereby a BEA operated Trident (which flew faster than most other airliners at over 500 kt true) was 'shadowed' by a Buccaneer which could fly about the same speed on a flight from Heathrow to Moscow in order to deliver a 'message' direct to the Kremlin by simply breaking away from the Trident as it was coming in to land.
Years later, I found this was feasible when a Yak 42 inbound to Farnborough for the airshow, when I asked for number of persons on board, replied '12 on the big aircraft and 2 on the little one'.
Apparently a Sokol Yastreb (which had been flight planned but for which no 'departure' message was sent) had taken off in formation with the Yak and unbeknown to en-route ATC had flown all the way from eastern europe tucked away underneath; it was only when the tower controller at Farnborough got both aircraft visual that this was confirmed; certainly I could only detect one 'blip' on radar.