I have to recommend signing up for IRIS, the Home Office's biometric alternative to Passport Control, at Heathrow next time you fly. I sing praises to lovely, CLEVER Show Me Your Wardrobe every time I bypass the monstrous Immigration queues at Heathrow for persuading me to sign up a few years ago on our first flight together to New York. (The little office is just after Security & just before Customs, on the RHS in Terminal 3. They take a digital photo in addition to the initial eye scan.)
She is a genius: the initial signing up process to register your iris takes maybe ten minutes and, in return, when you arrive at Heathrow (or Gatwick or Manchester) there is never, ever a line to use the IRIS machines. Of course it helps if you are not clumsy/spatially f**ked as you have to line your eye reflection up on a digital mirror glass contraption and it usually takes a few frustrating minutes to get this right if you are me. Still much quicker & certainly more interesting in a Star Trek type of way than lining up all cross eyed with tiredness to be stared at by a grumpy & doubtless over-worked Customs person.
I know some people have privacy & Big Brother type reservations about having their biometric details used in this way but, as they scan your passport anyway on re-entry, I can’t really see the difference in methods: your arrival will be registered for perpetuity either way. I rather like the fact that no one can ever pretend to be me using this system. And, of course, I travel so much that anything that cuts down my journey time wins with me: I've found that using IRIS is generally even quicker than a Business Class Fast Track voucher (not that I get to use those as much as I would like).