The Authority Announcement

It's sort of print through. It was caused by the erase head being physically a few cms away from the main video head drum, therefore when starting a new recording 'over the top' of an old one, there was a portion of tape
that was not 'cleaned off' that gets recorded over. Therefore during the time it took for the freshly erased tape to reach the rec heads, you got that effect. All domestic VCRs suffered from this effect. Professional VTRs solved the problem by having an erase head on the head drum, (important for insert edits) nevertheless it was always good practice to
bulk erase any used tape first.

So, that was a real backdrop and not a green screen?

It was an older, analogue blue screen installation, not a real backdrop.

And then you had the reverse at the end of a recording- where you had several seconds of erased tape before the previous recording appeared.

No c4 logo from what I could see

Makes sense now - a recording finishes and you get five seconds of static or so that then appears to run down the screen revealing the previous recording. Never occurred to me the gap between the heads was that great, but then I haven't seen the inside of a domestic VCR machine for ages.

It's not so much the gap is that great, but rather the tape speed is so painfully slow !

I'd assume he meant

And he is right; it does look like the Channel 4 logo if you squint.

Which is why the audio quality (on the linear tracks anyway, not the Hi-Fi ones) is so poor!

I think NTSC VHS runs about 50% faster than PAL VHS, in SP mode as well, so the audio quality must be higher (possibly the picture too?). Interesting that the difference in speed is much greater than the difference in frame rate.

The erase head on the head drum (the 'flying' erase head) was also needed for video add on or assemble edits too.

STV definitely were live, and were still doing Authority announcements as late as 1987. They never mentioned the main transmitters, perhaps because there was so many of them!

Border's one was recorded, voiced by Allan Cartner who was the station's senior announcer from 1961 until 1988. Cumbria, South Scotland, the Isle of Man and north and west Northumberland (the exact words and in that order) were all mentioned during the announcement. "North and west Northumberland" referred to the areas around Berwick, which at that time was part of Border's territory, and Haltwhistle.

It's interesting that some regions had stopped reading out an AA as early as 1983 (eg YTV), whilst others like STV and TTT continued until 1987 or later.

I assume that by 1983 it was no longer compulsory to make a formal AA, but some regions continued to do so anyway for a while? Why would the ruling have been changed/relaxed?