LHR - Fast track theoretically available. I say theoretically because only one station is assigned to it, which means it takes approximately twice as much to pass through it compared to regular lines.

Also, like at other UK airports, security is a massive shitshow... The new scanners speed the baggage check but then LHR runs everyone through full body scanners which are much slower than metal detectors, thus creating a massive bottleneck between the baggage unpacking station and the body detector. At some point there were so many people waiting for the detector that they covered the entire baggage unpacking area 🤷‍♂️