My AT&T sim card doesn't work in the UK

Remember I bought a pay-as-you-go sim card from AT&T last week? Although it was a painful process, I was delighted to have my own ‘local’ service to use.

I was deeply, deeply unimpressed when I switched it on at London Stansted airport and found zero signal. AT ALL.

There must be some ‘enable me for international roaming’ thing that needs to be ticked. Arse.