Jan Morris keeps promising that this is her last book. But this time, she means it. The 86-year-old author of over forty books, including the Pax Britannica trilogy, a whole slew of travel books, memoirs, collections of essays, novels, and, not to be forgotten, the Escheresque Oxford Book of Oxford. But Morris has recently delivered a new book to her publishers and asked them not to publish it until after her death. Though she’s going to be talking about it next week at the Wigtown Book Festival in Scotland. Provisionally titled Allegorisings, Morris has said that it will contain:

No amazing revelations. It is a little book, about everything from childhood to whistling to the exclamation mark. It stems from a conviction that’s been growing in me for quite a while, that nothing is what it seems, and that everything has one or multiple meanings.

I have always preferred Morris’s “history books” over the travel writing: her biography of Lord Admiral John Arbuthnot Fisher, Fisher’s Face, or Getting to Know the Admiral, prompted by a forty-year obsession with a photograph of Fisher, and her Pax Britannica trilogy about the rise and fall of the British Empire — master of both the incorporated detail and the footnote, Farewell the Trumpets has a set of footnotes that runs “1. They all died. 2. It sank.”

As James Morris, she accompanied the British expedition that scaled Mount Everest in 1953 as a journalist for the Times and it was Morris who first got the news of the expedition’s success to the Times, on the morning of Queen Elizabeth’s coronation. In the 1970s, she had sex reassignment surgery in Morocco, one of the earliest high-profile gender changes, and the subject of her memoir Conundrum.

The “travel writing” has always struck me as a little gushy — or maybe I’d just rather go somewhere than read about it, and since that’s not actually possible with the past, history books are the best substitute — but Morris’s rampant enjoyment of the world, year after year, is hard to dismiss. Yesterday, she turned 86. So, from the place Morris once called “the town of all towns,” happy birthday! And may you write at least another four or five books.