The most obvious inspiration for the story, of course, is The Boy Who Came Back From Heaven, which is a nonfiction account by Kevin Malarkey and his son Alex (that’s really their last names . . . you can’t make this stuff up) where they claim that Alex saw Heaven while he was a in a coma. The boy later recanted, saying his dad had planted the whole story in his mind, and it was a huge mess, but for a while it was quite a cultural phenomenon. There was even a major studio picture, starring Greg Kinnear.

I went to an exhibition at our National Museum that exhibited artifacts from Australia’s bushrangers. In the middle of the room stood a large, solid wooden door, soft with age, riddled with bullet holes. One of Ben Hall’s gang had been shot and killed in front of this door. The bullet holes were distinctive, and I thought I saw bloodstains, and the image was so powerful I almost imagined his ghost, up against the door. I thought about other doors, and what happens behind them

There was genuinely a wonderful, evocative scent that haunted me in my teens. I’ve no idea if it was a perfume I smelt once on a passing stranger or something I conjured from my own imagination, but I could evoke it at will, and once I had, it would tantalize me for days. I really did travel into Moorgate on the train every day with my friends for school, and I was once taken to an air show by my Aunty Anne (who fed me far too many boiled eggs). I’ve known for years that there was a story somewhere to be built around this “ghost” scent.

The story sprang out of a small, lovely book I picked up at a yard sale—The Ladies’ Letter-Writer—published in Great Britain in the early 1900s. You can see similar volumes on Google Books, all of them harkening back to an era when we relied so much on written correspondence. The sample letters cover many common occasions such as marriages, births, and deaths. The tone is very calm, the circumstances sometimes heartbreaking.