Interested to see this thread - always wanted to comment somewhere on these arrangements..... they are from one experience (the 2011 Heineken Final), but do highlight the potential issues with this system, which itself is a good and sensible idea. It keeps the station, and more importantly the platforms, free and allows large groups to be held where there's room for them.
The issue is if you're not going to the more 'popular' destinations (popular being 'more trains/capacity' or 'more well-known'), so if the original poster is going to London, the Valleys or towards Swansea, then you'll probably be ok. Be careful if you're heading somewhere like Birmingham or Shrewsbury....
There are a number of queues, all heading with destinations. Ours was Birmingham, and with Northampton having been in the final, was busy. There was also a separate queue for Gloucester. Most of those heading back to Birmingham knew that the XC trains to/from Birmingham were (a) relatively infrequent, and (b) only 3 carriages. Known because (i) we'd had to book days in advance to get a ticket on the hourly (or less) XC BHM-CC Saturday service and (b) we'd stood all the way from New St to Cardiff. So, we knew that the two XC trains going all the way to Birmingham would be busy and were in the appointed queue in good time - and (having lost) saw no point in being over-inebriated......
All well and good until the XC Birmingham train is due to arrive, which you can see. Unfortunately the security staff fill this one with people in the Gloucester queue and don't let anyone from the Birmingham queue on it. Great if you live in Gloucester as indeed the train does stop there. Not so good as by this time (8pm) there are no/few trains going anywhere else but west, up the Valleys or to London. And no one is going to pay the FGW walk-up fare to travel to London - but then you can't even get to the ticket office to buy a ticket either under this system.
So, by about 9pm, there's only one queue with any people (200 odd) left outside the station. And then the queue starts getting a little peed-off with the situation - we'd been there for over an hour going nowhere and knowing there were no more trains north of Gloucester. Needless to say, BTP start flexing their muscles at this point, and probably have a quiet word with the station staff about moving this problem somewhere else.
The last train (ATW?) to Gloucester is, of course, the preferred solution. Everyone decides to take it - after all, this must be an issue known by XC - and they'll be some provision at Gloucester surely ? Rammed to the gunwales, the two car 158 sets off (I think it was a Sprinter of some description) and arrives finally, some 30 minutes late in Gloucester. No one gets off - after all, everyone who wanted to disembark there did it off the XC Birmingham train. The Gloucester station guy said "he wondered why everyone got off the earlier XC train and it was very empty northwards. I was expecting it to be full."
However, the ATW driver gets off, and tries to get everyone off. Which obviously they're fairly loath to do. So, after some persuasion (and I'm not sure how), the train then goes forward to Cheltenham Spa - probably since it has to turn round there or something. So we all go up to Cheltenham, where upon we all besiege the poor ?FGW? station staff waiting to close up with the issue. Around 70 decide to call taxis and pay for themselves to go somewhere further north. The remaining 130-odd wait on the platform in a fairly mutinous mood. It's now about 11.30pm.
Meanwhile the train has turned round and comes back into the platform. The staff announces that it's going back to Gloucester where the station staff are beginning to organise coach transport back to Birmingham. All on the train on the strength of this promise, and back to Gloucester. Everyone gets off, and then looks for the station staff.
Amazingly, FGW (I think) have two or three staff there, along with the inevitable BTP presence. By this time, it's no longer a public order issue, but one of badly-let down customers with young kids (7/8 year old boys in Saints kit etc) wanting to get home.
And bless 'em, fGW Gloucester staff are as good as their word. They announce at about 00.15 that there's a bus on the way from Bristol Parkway and there'll also be taxis from outside the station. Those in the know about where Parkway is compared to Gloucester head immediately outside for the taxi where within 10 minutes we cram 5 in a shared cab and head north (never covered the M5 between Gloucester and Birmingham so fast). Finally get home to Birmingham at 01.30 on the Sunday morning.
Congratulations are to the fGW staff at Cheltenham and Gloucester (especially) for the way they handled a problem not created by them or their company. Also hats off the ATW Sprinter driver and guard - didn't have to take us back to Gloucester but did. XC (who I really do think would benefit from some fare and service competition - and I do like the even hours one company and odd hours another company idea for them) and the Cardiff station queue management people should be ashamed, and I hope fGW hit them for the costs of shipping 130 odd people around.
Lessons ? Next time I'll stand in the Gloucester queue. And I now also drive to Gloucester and get the train to Cardiff from there (which is also far far cheaper than from New St).
So beware !