I always thought CBBC were in charge of their own pres during their hours rather than network pres.
The way it worked then was that the whole afternoon came from TC9. NC1 would cut to TC9 at 3:20 and then everything was from them until 5:35*. In the lobby area of the studio were a couple of VT
machines and an operator from pres took the programmes down and played them from there. This meant that they could be a bit looser with timings and do fancy wipes and credit squeezes into and out of the programmes**
However once the programme was on air the gallery was by-passed and the VT machine was going directly out of the output of the studio. This allowed the gallery and presenters to rehearse and set up the next link. So the programme was the responsibility of the tape operator sitting in the next room.
So if there was an issue with the VT as seen in the Playdays clip then it was network control who put the slide up because TC9 wouldn't have been in a position to step in immediately... in fact the gallery might not have even noticed as they weren't watching what was on air. So the network director would have put up the slide and then wait till TC9 were able to take over.
The morning CBBC block was different as that all came from presentation, with recorded links.
The other reason that network would get involved during CBBC programmes is if there was an issue with TC9 or they lost the line from it. Though of course if this happened the tapes with the programmes on were on the other side of TVC
so they'd have nothing to play
*the network director didn't have much to do during CBBC but despite it all being from the same source, the schedule in the automation still had the programmes as seperate items and the director had to manually 'take' them when they started. This was for timing reasons and later on to trigger the EPG
** this changed when wide-screen CBBC programmes started. TC9 was still 4:3 and so if a 16:9 programme was scheduled that would come from pres in the normal way, not from the studio. This meant a straight cut into and out of the programme.
Even though I think TC9 was built so it could easily switch to 16:9 the issue was how it would control the wide-screen switching. These were the days when the were seperate analogue and digital versions of BBC1 and 2, and so there were ARCs all over the place and different AFD and wide screen switching signals sent for each programme. Also the two aspect ratios were played from different tape formats. It was very complicated
As time went on more and more of CBBCs programmes went wide-screen and so network control ended up playing everything