Captain Bannister was asking Air Traffic for the preferred landing times for the 3 Concordes, and said that company had asked that none landed 'on the hour'. Before the hour, or after, was OK, but not on the hour.
Why was that?
To maximise live TV coverage (read "free publicity") I guess.
Not so much with the BBC as they were live throughout; but many TV networks worldwide were taking feeds from LHR on syndication and would have been away at bulletins at the top of the hour.