It turns out there's a big difference between Avis and Hertz in England. I'm in the preferred programs for both companies - have been for ages. Whenever I turn up at the Hertz desk, the response every single time is "we don't have a car for you". At Avis, I can turn up, my name is on the board and I can just get in the car and go. As it should be. It's worth pointing out that back home in America, both Hertz and Avis work perfectly in this respect. But in England, Hertz is just crap in a way that only the English can manage. So if you find yourself renting a car at an airport in England, just don't go to Hertz. It's not worth the hassle.