A couple of days ago I was at T5, as usual I walked the looong way down to the fast track, on my way down I noticed some of the non fast track lines were much less crowded than the line at the fast track, so I decided to skip the fast track and jumped the barrier into one that had almost no people.
Not so long after me, another fellow made the same choice, but he was so unfortunate that one of the gards noticed him. The guard came up, asked to see his ticket and then sent him back to the fast track queue.
Now I wonder, does it mean that if you are eligible for fast track on Heathrow T5, you are not allowed to enter another line?
Or was it just that the guy (and I) took the liberty to jump the barrier, or???