Another afterthought....
A few years ago I gave a friend I happened to run into in the chaos at LGW before Immigration my boarding card from Jersey, as he was in a hurry having just landed from the Middle East. He went through that Channel, and I went through the passport channel.
Can you still do that? Or is it prevented by qwertyplop's magic and mystical one-way mirrors and invisible controls? I do know that many of the passengers from Ireland last night simply showed their passports to get through that channel rather than confront the scrum to go the other way, because I was in the middle of a group that did just that, so I guess it still works the other way round as well, if you have a boarding pass. It would be useful to know.