Cue dot on BBC One start-up

https://www.tvark.org/?page=media&mediaid=115370

Just wondering why there’s a cue dot at 1:35” on this BBC One start-up?

I know it’s before the news but surely there’d be talkback between NC1 and the News Gallery? So why the cue dot?

Cue Dots were standard for all live programmes ISTR - you'd see them before every news bulletin. They weren't just used for OBs or off-site studios. Cue Dots weren't just used as a backup for when talkback failed - they were routine. (So worked even if someone had turned down working talkback...)

NC1 and NC2 also had remote control of the red lights in studios at TV Centre - so Pres could flash them at 2'00" to TX and make them illuminate when the studio was on-air (kind of like a tally light from Pres). These signals also inhibited things like 'Bars and Tone to line' switching...

You might also see them being tested mid programme. This was when pres were lining up with a live programme and would check they could see the dots at their end.

Sometimes used by regions to check they had successfully opted out.

In the days PPBs were simulcast on BBC and ITV, you'd often see on ITV the BBC cue dot top left, and ITV's top right on screen together. (The 70s really were that dull)

I don't understand why the Beeb didn't just send Thames the clean feed directly from the VTR?