[bbctvtechop]

A couple of quick points on this. Firstly by '2 way clean feed' I assume you mean it's the clean feed for the two-way, not a clean feed in two directions which isn't a thing. 

Secondly satellite feeds are one way, but that's not to say you can't have two, one in each direction. So the guest is being uplinked to the BBC and a reverse vision uplinked by the BBC back to the studio where the guest is. Doesn't happen often and rarely in news unless the presenter is on an OB. Though it's more common to use a low latency IP based reverse, this is always the case for autocue feeds for obvious reasons. 

A lot of satellite lives for news are two-way via satellite as the clean feed is sent back over satellite to the uplink truck 

Reverse vision via Zoom or other services like Skype, Facetime and WhatsApp is used sometimes. Sometimes the contributor had to see what's happening in the studio. One example is the kids show Saturday Mash Up, the contestants playing a game at home get a reverse vision from a seperate output of the studio to play their games

"2 way clean feed" is the awful name used by the BNCS system, not my terminology. To my knowledge all it does is one-way audio routing back down the line (incoming audio is present as soon as the source is selected into one of the OS destinations), as well as preventing any other control room from taking "2 way clean feed".

I would have called it something like "Gallery Lock". 

BNCS does actually build up a 2WCF queue in the order that galleries/radio cubicles request 2WCF. Then as the gallery in control releases 2WCF, the next in line automatically receive it and their audio starts flowing down the line instead. MCR and a few other central controlling areas have the ability to reorder the queue, release control from the gallery that has it, or boot out galleries from the queue.

So on a busy day when one correspondent is in demand, the newsroom decide which outlets get the correspondent in which order and send MCR the list. When the line is up, MCR can phone the first gallery and get them to take 2WCF. Once they have control of the line, they can call the second, third and fourth outlets and get them lined up in 2nd, 3rd and 4th place in the queue. Once (say) the news channel has done with them, they release 2WCF and (say) 5 Live then automatically receive it as they were next in the queue. And repeat.

Interesting comments on reverse vision feeds. To my knowledge none of the thousands of guests I've put through to BBC galleries have ever had a reverse vision feed supplied to them, in any format or technology. I have seen Autocue feeds being sent down IP lines, but not as part of a reverse vision feed per se, but as a standalone feed for presenters on location.