They really need to fine tune the immigration clearance at large UK airports. Today there is an EU/EFTA queue and an "Everyone Else" queue.
The everyone else queue should be divided into 'those needing visas' and 'those not needing visas'. In my case I am a Swiss resident with a Canadian Passport married (almost 20 years) to a British national. In other words of little, if any, risk of overstaying and who would probably be given leave to reside if I ever asked for it.
I often get stuck behind a flock of ex-USSR call girls, the large non-English speaking families, or a bunch of people who don't know how to fill out a landing card. I rarely take a minute at the desk, after waiting for up to an hour.
I would be willing to preregister (and even pay a fee) for speedy-clearance (tm).