Many years ago, when I was a student, I suddenly developed a terrible toothache. I’d recently moved from Italy to the UK so didn't have a dentist yet, so I called the NHS for help. They arranged an emergency appointment at a local clinic that same day—a Sunday. I was very impressed!

The clinic was on one of those slightly dodgy-looking industrial estates. To get inside, I had to walk through a plastic strip curtain, which made it feel more like a butcher’s shop than a dental practice. Plastic chairs. Dirty floors. Dodgy peeps waiting. Still, I was grateful to be seen.

I waited my turn, then spent about half an hour in the chair while a man drilled away at what turned out to be a cavity. He put in a filling, and afterwards I asked what I should do next.

“Well,” he said, “I don’t know how long that filling will last. A week, a month, a year—who knows?”

Then, he recommended that I go and see a dentist.