On my desk is a jiffy bag from the London Library containing two of his forgotten books. It’s been there for weeks, but I’ve yet to open it. I’m doing so now, tearing through the packet’s yellow paper. One of the books is L’Empereur Alexandre II, published in 1884. It’s the other volume that makes me gasp: Russie et L’Alliance Anglaise, published in 1906, but with the following inscription written shakily and belatedly on the flyleaf: ‘To her Royal Highness the Duchess of Kent, respectful homage accompanies my highest regards for the health and happiness of your noble and gracious Royal Family.’ And then, beneath it, his signature in the same blue ink: Nicolas Notovitch, 15th January 1939, Paris.

Running my finger along the words, I have the uncanny and vertiginous sense of uncovering a piece of history. No one knew that Notovitch had lived so long. And I had forgotten in my enthusiasm for the story that under these inventions lies the kernel of something real. For a giddy moment, that assemblage of mirrors lines up perfectly. The prey I’ve been stalking through the secret books swims into view. Our eyes meet briefly. It’s the one activity we’ve obviously got in common: inscribing copies of our work. There’s something pathetic about this one: thirty-three years after it was published, after an interval that included the Russian Revolution and the Great War, Notovitch made a gift of this superannuated text to a woman who would never read it; judging from the tightness of its pages, I’d say no one ever has.

This isn’t the book of his that will be remembered. By the time of its inscription, he was old, older than I’ve so far dared to imagine him: eighty, shortly to turn eighty-one. He handed her the book, after a dinner, a soirée. The country of his birth vanished in 1917 and he is by now an adopted Parisian.

‘Monsieur Notovitch, vous êtes gentil,’ the duchess says, when he offers to inscribe it. Did she associate the courtly old gent with a notorious tale of forty years before? Did the name stir a fragmentary recollection: the story of an old monastery, India, a suspected Russian agent? ‘Notovitch. Notovitch. That name is familiar.’ ‘Why yes, perhaps you’ve read my Souvenirs of Sebastopol, or The Pacification of Europe? Seen my drama, Mariage idéal?’

‘No, no – it’s something else, I’m sure of it.’

Looking at the title page through his reading glasses as he tries to shepherd the unruly syntax of his inscription, the old man feels his heart tighten. He’s being mocked. A sly compositor more than thirty years before inserted a rogue word repeatedly in the fine print of the list of other works. It’s there, and there, and there: three times, like an obscene sound from the back of a rowdy classroom. ‘With illustrations jésus’, ‘Available in octavo jésus’, ‘In cloth jésus wrappers’. The word is street slang for a young male prostitute, but when applied to Notovitch it has other, obviously demeaning, associations.