Thought this might fit in here. Is it acurate?
Pretty close, but I did spot a couple of things.
Even when the regional studio is off air (or "out of circuit" to use the more common term) the network signal still takes a round trip through the regional centre on it's way to CCM. But only as far as the opt switch in the Central Technical Area, not the studio.
The soft opt is the idea of taking the network feed to air through the regional studio a few minutes before the opt so you get a clean transition to local material - the video suggests it's the cut away from network rather than going into circuit carrying network.
You can see it happening here:
Putting the BBC East regional news on the air in 1983 with Judi Lines... pic.twitter.com/TF52RWJ6nW— The Telly Box (@tellytvbox) March 7, 2021
She has already soft opted before the video starts, that is to say faded up network sound on the right hand fader and selected the network vision source then gone into circuit so Michael Fish is routed via this desk.
Once the weather ends she fades down the network audio and cuts to the ident, then fades up her mic and begins talking.