Sitting in her pretty London parlour, with its china figurines and pale-green wallpaper, P.D. James puts her hand palm down on the table and asks me to do the same. Hers is beautifully shaped and heavily veined and carries two ornate silver rings. Mine could use a wash.
"You can try to hold back time, but you can't do anything about your hands," she says. "Compare them, my dear. An old hand and a young one. There's nothing you can do about it." Youth is perhaps a relative concept when you're about to turn 90, which James does today.
You just have to be careful and say, 'Is this really good enough?'
Look at what her hands have accomplished in nine decades: held children and great-grandchildren, signed important political documents, written 20 books that have given readers countless hours in faraway worlds where murderers never prevail. She has led an exemplary life of public service, private sacrifice, intellectual achievement. If there were a hand Olympics, hers would win gold.
"Yes," she says briskly, picking up a china teapot and pouring two cups. "It is quite consoling to think what they've been busy doing." At the same time, it's clear that she's thinking: Let the fuss be over with so I can get back to writing. Her fingers itch to return to the novel that she's currently working on - a complete departure, she will only say that it is not a mystery, nor does it feature her famous fictional creation, the imposing poet-detective Adam Dalgliesh.
But Dalgliesh fans needn't fear: She intends to write another story about him, if she can find time between birthday celebrations (her publisher is throwing her a giant party with friends flying in from around the world) and political obligations (she sits in Britain's House of Lords as Baroness James of Holland Park, and no, she doesn't know when Conrad Black will be back in that chamber).
"But it is important that I don't go on if I think I can't maintain the same standard," she says. There is a dread of turning into Agatha Christie or Ngaio Marsh, churning out pale imitations of earlier triumphs to feed a hungry reading public. One of James's mysteries takes three years to write, from the research (her former life as a magistrate and policy adviser in the Home Office always proves useful) to the detailed outline to the actual writing, which she does at her kitchen table.
"Writers love writing, and your readers are longing for a new book, so there's a great wish to provide it for them. You just have to be careful and say, 'Is this really good enough?' "
Would she know if her gifts were going? "Oh, undoubtedly. It would be the language, the quality of the writing, all sorts of things might go." Her last novel, 2008's The Private Patient, is one of her favourites, and she was able to finish it thanks to the relative peace of a convalescent hospital, where she was being treated for heart failure. Late last year, she released a non-fiction survey of her preferred genre, Talking About Detective Fiction, and donated the royalties to Oxford's Bodleian Library.
It should feel morbid talking blithely about how much time she has left on Earth, but it doesn't: Death is the one constant in her stories, each bludgeoning or poisoning or suffocation described with precision, and the natural balance restored in the end with Dalgliesh's calm j'accuse. As a child, she was death-obsessed, and would imagine at the beginning of the school holidays which of her schoolmates might not live to see the end. That has eased with time, but only just.
"I remember looking forward to the millennium and thinking, 'Will I live to see it?' But here I am at 90," she says, with her hand resting on an early edition of Charles Dickens's A Tale of Two Cities, a birthday gift from the staff of her London publishing house, Faber and Faber. "That does seem surprising."
Then, tea finished, she takes a delivery from the House of Lords - it arrives by special parliamentary mail, containing the next day's business - and says a cheery goodbye at the door. There's so much work still to be done.