My brother's has too, all of one hedge gone. I have seen it all over the place too. Absolute infestations. At first I thought that it was because invasive species (which it is) has no predators, but my brother said loads of birds had been coming and feeding on the caterpillars, but clearly not enough.
Guess we'll be seeing a lot of box tree moths this summer. They are quite pretty, so not all bad.