I think we waste more time and money on this matter than anyone else. And whatever ludicrous security check you can think of, the UK will implement it first.
I don't know.....
I think the jittery knee-jerky post 9/11 USA comes waaaay ahead of the UK !
They've got it all ... everyone entering the US has to pay an annual subscription fee for a magic ESTA, fingerprinting and photographing all passengers, full body scanners, gun toting air marshals on all flights etc. etc. etc.
And of course heaven forbid you're a non-US citizen wanting to learn to fly in the US..... enjoy the extra scrutiny and form filling !