Incompetence
Folks, don't make excuses for this incompetent shower 'running' LHR. They have had sufficient time for dry runs, but still they cannot get it right. Equipment breakdowns are also down to shoddy workmanship, but then that's what the UK is becoming - shoddy.
As previously stated, all that BAA and their Spanish owners are after is your money, and they do not care much about how you are dealt with, nor delays; after all, if you are delayed, you are more likely to use the stores in the terminal.
Try Paris, Frankfurt or Amsterdam, as they all leave LHR way behind, and the staff are generally more friendly than the often rude staff at LHR.