While the sweet melancholy of regret has its poetic attractions, I still like to think that my best writing is ahead of me. Even so, at 56 I’m starting to think about what might be possible in this lifetime. I could still be around for another thirty or forty years. But it’s far from guaranteed that I’ll be able to write or think as well as I’d like for all of that time.

I guess that every writer has to come to some accommodation about how ‘phase three’ is going to work. Unless we die suddenly, and early, we get a bit of time to work out the career priorities. Dying prematurely used to be more common, of course. Many authors have departed leaving books in progress, or simply waiting as ideas; and unless an actual writing retirement is taken this risk seem almost inevitable. Death can be a motivating yet cruel shadow. A guillotine that falls both with and without warning.

Robert Louis Stevenson was still working on a family epic set during the Napoleonic Wars called Weir of Hermiston on the day he died from a cerebral haemorrhage. It was published in its unfinished 242-page form in 1896. He had enthusiastically told those close to him how the story, which he considered his finest, would play out. Henry James died in 1916, leaving the unfinished manuscript of The Ivory Tower, which was published the following year. An $8,000 advance from his publishers (secretly donated by the author’s friend Edith Wharton) had helped the work along but hadn’t got it over the finish line.

Sanditon, the later of Jane Austen’s two unfinished novels, was abandoned in March 1817, just four months before the author’s death at the age of 41. Whether it was actually given up for creative or health reasons seems unclear — but it does seem that she was interrupted. Austen has had the honour (or indignity, depending on your outlook) to have had the book completed by numerous ‘continuators’ in the 200 years since. None of these has created a work as notable (or filmable) as Pride and Prejudice or Emma.

Mark Twain worked unsuccessfully on one particular novel for over ten years before his death in 1910. There were three drafts of The Mysterious Stranger (also known as Schoolhouse Hill and The Chronicle of Young Satan) but none of them was ever completed. While he had become obsessed by the theme of the story – the failings of organised religions – Twain was unable to come to a happy conclusion about how the story should represent his ideas. This hasn’t stopped other writers and filmmakers going about their business of adaptation, editing and generally pulling the material apart and sticking it back together again. Not only can dead authors not be libelled, they are also not in a position to complain about the actions of other writers who decide to use or abuse their not yet fully realised ideas.

Perhaps it was for this reason that Vladimir Nabokov left strict instructions that any incomplete works should be destroyed after his death, in 1977. We do know that Nabokov was a perfectionist and would have been unhappy that a work that was not fully realized could be seen by the world in its unperfected state. In any case Nabokov’s son Dmitri decided not to honour his father’s wishes and kept the fragments of his father’s final unfinished novel intact. The son’s decision-making process isn’t completely transparent but in 2009, the Lolita author’s unedited work, The Original of Laura, was eventually published — to some critical disappointment. Where are those reliable heirs when you need them?

It’s believed that first-time novelist Emily Brontë was in correspondence with her publishers about a follow up work to Wuthering Heights when she succumbed to illness at the age of 30. It’s also thought that her family may have burned whatever it was she had started. It’s hard not to wish to know more about those books the author never quite got to. If Emily could produce Wuthering Heights first time around, what could the next one have been like? Maybe Tolstoy and Dostoevsky had something better in them. Zola and Flaubert too. Perhaps Dickens’s unfinished The Mystery of Edwin Drood could really have done with the master’s touch in working out the revelatory ending. And what might Shakespeare have written after The Tempest? Even if those post-retirement gigs don’t always work out so well, he was still at the top of his game when he took the step of leaving the stage in Prospero’s cloak.

As readers, we get the books that their authors managed to write. They may not have lived up to their creators’ expectations. There may have been better, more transformative, more moving and groundbreaking works that never saw light. As writers, we only get to write the books we have the time, energy, commitment and ability to complete with our allotment of psychic energy. It seems a fair conclusion then that some of the best books never got written and that the same situation will pertain in the future. Authors can pass their writing peaks before they are able to manifest their greatest ideas.

This thought troubles the mind — but it will not stop authors trying. The process of writing is nothing if not compulsive. I’ve tried giving up and it doesn’t really work. Something soon comes knocking, begging for attention and I’m back at it again. In half-joking moments I say that I’ll switch to painting when my mind turns to mush and I can’t remember which words to use and what order to put them in. I’ll also have the benefit of being able to listen to Radio 4 while I’m working. But in the meantime, with this window being closed gently by the turning years, I have some works to be getting on with: a good few novels, some screenplays and a long series of graphic novels.

And a new and inspiring thought appears: it’s not as if we are vegetable growers whose wares are about to go out of date and rot; unlike us written work does not expire. One of the great beauties of digital technology is that nothing need ever go out of print again. From now on the world’s literature supply can keep on growing forever, accumulating in the server vaults and eternally poised ‘on demand’. If we have a wish that our work, however incomplete, can live on into the future it has been fully granted. So now it’s back to the novel and to working out who’s going to get the job of literary executor.

Keith Tutt is a Bafta-winning scriptwriter and author, who lives in Norfolk.