AS luck would have it, I was out when the postman tried to deliver my copy of The Mirror & the Light.

I stared at the card he left for a while, as if it might metamorphose into the book before my eyes. Then, on retrieving it the following morning, I turned it over in my hand, taking pleasure in its solidity, its luminous cover and its tantalising promise.

I only had time to read the opening sentence: "Once the queen's head is severed, he walks away." But there it was: Hilary Mantel's inimitable narrative style, and I realised it would be like catching up with an old friend. Thomas Cromwell and I would pick up exactly where we left off.

Mantel is a mistress of suspense. Who knows why it took her eight years to deliver the third and final part of her Wolf Hall trilogy, which goes on sale on March 05. Perhaps, after producing two Booker Prize winners in a row, the weight of expectation cramped her creativity. Or perhaps, as some have suggested (but she has denied), she couldn't bring herself to send her kinder, wiser, version of Henry VIII’s fixer to his execution. But as a marketing tool, it worked.

Rarely has there been more public fretting over the progress of a novel; or more speculation about the date of its publication. Amidst the fretting and the speculating, Mantel carried on unperturbed, producing the short story collection The Assassination of Margaret Thatcher, an essay on Diana, entitled The Princess Myth, and the 2017 Reith lectures; anything, it sometimes felt, other than the work her fans most craved.

The first hint The Mirror & the Light might finally be on its way came last May when a mysterious billboard, featuring a Tudor Rose and the words "So Now Get Up" appeared briefly in Leicester Square. The message may have been oblique, but it was not lost on the legions of readers who took to social media to celebrate. Only the Game of Thrones logo with the words "Winds of Winter is Coming" – heralding George RR Martin's equally elusive sixth A Song of Ice and Fire book – could have caused a greater sensation.

From the moment Mantel's publisher HarperCollins confirmed fans' hopes, it has been clear the launch of the Mirror and the Light would eclipse everything else on the literary calendar this spring.

As the date has neared, the frenzy has grown. By autumn, a reading guide, The World of Wolf Hall had been issued, along with new editions of Wolf Hall and Bring up the Bodies, for those who wanted to play catch-up over Christmas.

Every day now, the Twitter account for 4th Estate Books (the imprint publishing the book) brings fresh news of promotions, window displays and Mantel-related events. Things took a surreal turn when Waterstones Hove tweeted a photograph of two dogs – Nettie of Cleeves and Hal VIII – in Tudor costume and encouraged others to post similar pictures of their own pets.

The publication of Margaret Atwood's The Testaments, the sequel to The Handmaid's Tale, saw midnight openings, including one featuring white-hatted, red-cloaked handmaids and readings by Atwood herself.

For the final book of the Wolf Hall trilogy, Waterstones announced a limited £100 clothbound edition (with extras, including an essay by Mantel), a The Mirror and the Light-specific gift voucher and a signing event for 200 fans at Waterstones Piccadilly.

Mantel is held by many to be the UK's greatest living author. She is incapable of writing a dull sentence. But this degree of adulation for a producer of highbrow historical fiction is still intriguing; especially since her brilliant earlier novels were not best-sellers.

"I think what has made the Wolf Hall trilogy so significant is that it's tapping into two current streams at once," says Stuart Kelly, literary critic and former Booker Prize judge. "Firstly, it taps into a fascination with Englishness, but it's also about the Machiavellian politics. I’m not saying Thomas Cromwell is the Dominic Cummings of the 16th century, but there's a fascination with the machinations of power. The book’s presentation of the country is Merrie England and Perfidious Albion rolled into one – and it's a jolly good story."

Also impressive is the way Mantel has recast Cromwell, a man previously portrayed as a monster, in a more positive light. "To take Cromwell, who has been so well done in works like A Man for All Seasons, where he is the absolute villain, and make him into the moral core of the novel, it's a brave thing to attempt, and I think she has done it very well," Kelly says.

Whatever the appeal, Wolf Hall and Bring up the Bodies bestowed rock star status on Mantel. Since the latter was published she has been made a Dame. The two books have been turned into an award-winning BBC drama series starring Mark Rylance as Cromwell. Rylance's performance was career-defining, his agile face expressing every fleeting thought, his presence dominating the screen, even when he was lurking in the shadows.

The popularity of the series drove demand for the books, just as demand for The Mirror & the Light is now driving demand for a televisual update. A draft is said to have been sent to Peter Straughan, who adapted the first two, so he could start work on a sequel to be broadcast in spring 2021.

Though the whirlwind around The Mirror & the Light is good for HarperCollins, Mantel and her fans, it may be less welcome to others whose books are being published the same day, including Hadley Freeman, author of House of Glass. Who would want to fight for the scraps of air time and newspaper column inches that will be left after The Mirror and the Light has been dissected? Freeman herself jokingly acknowledged this when she tweeted: “Hope you don’t feel overshadowed, Hilz.”

And the literary juggernaut won't stop there. Debate over Mantel’s latest masterpiece will also dominate the book prizes, particularly the Booker in October.

"If I had been asked to be a Booker judge again this year I would have said no. They will be on a hiding to nothing,” Kelly says. "If they give it to Hilary again, it will be: 'They never even thought about this decision.' If they don't give it to Hilary, the headline will be: 'Hilary misses the triple'."

Faced with a similar dilemma last year, when The Testaments was the big beast, the judges split the prize between Atwood and Bernadine Evaristo, author of Girl, Woman, Other, a decision that pleased no-one and is unlikely to be repeated. But this is an issue for another day.

For now, let's revel in the knowledge that, in 2020, an age of smartphones and PlayStations, so many people still derive pleasure from the printed word. People like Julie Danskin, manager of Edinburgh's The Golden Hare – last year's Independent Bookshop of the Year.

"I have never been that interested in Tudor history, but there is something about the way Hilary Mantel writes that just pulls you in," she says. "It's there in the first scene of Wolf Hall where Cromwell is a young boy having his head kicked in by his dad, and you straight away know this isn't going to be a normal story about monarchy and the madness of Henry VIII."

The Golden Hare is a small bookshop with a wood burning stove, and little capacity for special offers and early openings. But there will be a big display on the day and Danskin is confident there will be more pre-orders for The Mirror & the Light than any other book this year.

"It's something we talk about quite a lot, why a certain author attracts a lot of hype," she says. "Marketing departments have a huge role in that. But I think Hilary Mantel creates her own hype because she has so much of a following and so much respect.

"People read her who wouldn't normally pick up literary fiction. There is something about her writing that manages to transcend the elite Booker set. The books are page turners as well as being beautifully written."

The Mirror & the Light goes on sale on 05 March. Fourth Estate, £25.