I tried to apply all this last week as I queued for 1h45min to go through security at South Terminal, Gatwick.
And that is indeed a national disgrace.
I use either LCY, BHX or LTN and AMS twice weekly, and have used other airports from time to time. In none of the above four have I *ever* encountered a queue of that length (nor indeed in LHR or LGW, but that's only about 3 times and I was probably lucky, and the queues were still not insignificant).
15 minutes is the *most* that people should have to wait. If that isn't feasible, either employ more staff or cut the number of flights by law if necessary.