In the mid 60s, when the station used to cease transmission at about 10.30 each evening, the closing announcements were always accompanied by the same piece of music, 'Elizabethan Serenade'. It's a hauntingly beautiful piece and a quick search on the Internet will soon turn up a recording to listen to, if you've not heard it before.
The piece was written in 1951 by British composer Ronald Binge, though when first recorded it was called 'Andante cantabile'.
At close-down, over the music, the (prerecorded) announcer gave details of the station, its location, the transmitter location, power output, highlight of the programs for the next day and so on. It was pretty much the same over and over every night. I'm sure that if someone were to play a recording of the music to old announcers like Bob Hargreaves and Bob Perry, they could recite the shut-down script from memory, even after all these years.
Of course, what the viewers never saw, nor probably suspected, was the rush by the duty technician and video and audio operators out of the door and on their way home, even while the last fragments of sound still echoed down the corridor.