I have a UK passport by virtue of the fact that my father was born in the UK (mostly by accident - another fun story). So I also know about the visa waiver program - it used to cover me too. Until one day I flew into the US briefly, on my own plane, to visit friends in DC as part of a long trip. When we arrived at Dulles, the immigration officer said there was a small problem. The operator of my plane had never signed the visa-waiver treaty, and so despite the fact that I had entered the US 27 times previously on that same passport, without a visa, they would now have to decline me entry.