Interesting and yes I have had this before.
To be honest I usually go to the desk when I am there and mention that I am group 0 and ask the team how they would like to handle things (so sort of giving them the impression they are in charge when of course its really asking when are you going to board me). Most times they will just say come through and then you are in the holding area.
Now at T5 the issue is when they then invite through all the Group 1 passengers as well. The best teams remember who the Group 0 or 0's are and then come and find you and ask you to board and then take you to the escalator when they switch it on and open up the Tensa barrier. That way you get on first. That is really how it should be (and from what I can see at A gates it is how the Prem's are also managed).
As to the endless debate about are we pre or post those needing extra time to board it is a tricky one. My gut feeling is there are only usually 1-2 Group 0's on a flight (if any) and all of us by definition are used to airports and are pretty nifty at getting around so we can be out of the way in 10 seconds (even in Short Haul). Those who really do struggle with boarding and need time there must be nothing worse than the feeling of people behind who you will percieve are all huffing and puffing (even though we all understand and of course aren't!!) whilst you try your best to battle with your challenges boarding (no one wants to be slow to board) - however if there is no-one behind then you don't have that pressure etc etc. For this to work though we would need to know this is the rule or not as the case may be. I don't mind either way but a bit of consistency would be nice........
Having said that I did get a right scolding once for walking down to the the jetty when I was told off with "I was waiting to let this lady to pass - are you really so rude......" to which rather than say anything I just let them pass - seemed way easier to just get egg on my face than try to explain the whole thing.........
FD.