Amazing how one question can provoke such a range of responses; I am grateful for them all.
The film is on Twitter, posted by Captain Brent@Birdseed501. It claims to be 1972. I say 1971 but, either way, I'm not old enough to remember.
It's off-topic but Channel Airways (the mixed-fleet outfit, not BEA Channel Islands Division) DID operate schedules through Leeds Bradford, namely the Scottish Flyer service, circa 1969/1970.
I'm meeting an ex-LBA ATC chum later this month. I must remember to ask him about this subject.