Every time I have arrived into Heathrow in the last three years I have had to wait at least two hours to get through immigration.
Far be it for me to question the validity of your assertions, but ....... was that once or twice you flew then ?
Okay, its a while since I did lots of long haul, but either you're someone who needs to be checked thoroughly, you're the statistical tail of the probability curve or your memory is faulty.