Around 18 months ago I was on an early BA flight out of T5 to Athens, it was tight I knew and I underestimated just how long the bus took from the big Premier Inn round to T5 so I was up against it. Had an e-boarding card on my phone, ran from the bus to the bag drop with 2 mins to spare. The agent took my bag, tagged it and (so I thought) dispatched it down the chute and told me to run to security. (I am not a serial 'late arriver' this is the one and only time I've had to run like this).
I arrived at security to be told I was too late and to go back to the BA passport desk as there was a "message on the system".
At the passport desk they said I had missed the flight and to go to customer services where they fleeced me of £300 to get on the next one (the next guy in line had to pay £800 as I had taken the last economy seat I overheard every one of his swear words!). Whilst I paid a BA person brought my bag which hadn't been sent down the belt after all (funny that).
I wrote to BA customer services and was completely ignored - twice! I now avoid T5 at all costs (in fact I almost always use the train now for domestic travel). I have flown out of LHR and MCR for many many years and have never been treated like that and in the old T1 staff did their best to help you through if they could. T5 is a machine - it may be a very efficient machine but we are now cattle and the operators of that machine behave in a very inhuman way. If this is mass travel then no thanks....