So. I have a ticket on British Airways, from Berlin to JFK; with a connection in London. However, the Berlin-London leg lands in Heathrow, and the London-JFK leg takes off from Gatwick. And BA has given me 3 hours and 15 minutes to transfer. Assume that I cannot change that, please.
I've discovered a fantastic guide to "how to get from Heathrow to Gatwick", and am confident the travel time between airports is doable (especially since I will not be using any checked baggage, I will only have my carryon). I also have ensured my passport is up-to-date. However - I've been hearing a couple horror stories about the passport control area of Heathrow, which a) actually run counter to my own experience and b) seem a little unlikely (someone told me their sister had a three-hour wait in line, but that was their sister and it was in the middle of summer; I am alone and flying on an odd day in fall). But I'm spooked enough to want to ask.
So - what exactly is Heathrow's passport control process for a US passport holder, who is only transferring airports and then leaving for the US? I've seen people elsewhere talk about an "e-passport" kiosk, would that be something I would be able ot use as a US citizen? Is there a streamlined "just passing through" passport line I should look for? I would already have my passport and my boarding pass for my connection in Gatwick out and ready, and again, I would be travelling only with my one carryon bag and a purse.