Originally Posted by
MADPhil
It seemed worth the money to avoid having to anything each time I visited the UK. Before US passports could use the E-gates I used to swap passports without changing anything and it always worked but as use of the API has expanded I keep thinking they will start caring.
You do realise that you can have US passport details on the booking, and just use your UK passport at the e-gates at Heathrow? No need to swap your details around. And if they ask at the departure airport, just show them your UK passport. No need to apply for ETA.