Originally Posted by IAN-UK

I think you haven't quite got it . The e-visa entitles you to use the e-gates. There's a whole line of them. You simple feed your passport in, much like at Heathrow, and bingo. No need to show your visa to anyone, no need even to scan it. No agent involved. No stamp in your passport.

I have never seen queues for the e-gates: you can be through in seconds rather than minutes,

Much the same on leaving, which can be useful if you hit a time of umra-heavy departures.