On Tuesday night, all airport egates throughout the UK went down for just over four hours. It was a technical problem.
However, it caused hours of delays processing people entering the UK.
So, when people ask how long it will take to get through passport control, don't always assume the egates will work.
Even if they are up and running, they may not work for everyone. I had an issue last year where the info the airline reported to the UK was different that what was on my passport. I had to go through a quicker line but still added a bit to my time.