Question did they get stopped at the gate before security like us and were the BA staff now more aware of the situation etc ? Thanks

For some reason they chose to do a manual bag drop (don't know why) and the agent asked to see it at that point...

Not sure what the subsequent process was with any boarding card but they subsequently got through the gates at conformance without any difficulties...

Another update
 

Just heard back from BA customer service after I requested a status. Essentially they said sorry for the inconvenience etc etc and here is a voucher which can be used for future travel . Thanks for the voucher but no further light was shed by them on what had occurred and I'm presuming they don't intend to for whatever reason.
Dont see the point of pursuing this with them any further. Lets see what happens next time in T5, one would hope for a better experience but I'm not holding my breath.