I'm curious about what other colleagues think. I do think it's a bit hokey to say that we can have staff in the room but they can't look at the documents.
If I come in with a research analyst from my team and have a document but I can't give it to them, and then I read certain sections of it to get their opinion of it, they're still getting the information. Presumably, the purpose of having the staff there is to have a conversation and research support, but if I have to verbally read them the section so we can discuss it, instead of their being able to look at it and read it at the same time that I read it, I don't know what's achieved by that.
If you can't bring notes out of the room, if you can't bring in any kind of recording devices.... Of course, you're not allowed to leak, and there are parliamentary sanctions associated with leaking, but beyond that I think there are significant measures to prevent individuals or the one staff they bring in from leaking information. It's pretty standard that in camera we have a staff member.