Howls of outrage greeted a speech in 2013 by Dame Hilary Mantel in which she described Kate Middleton as “a jointed doll on which certain rags are hung”.

Howls of outrage always seem to greet Mantel when, every few years, one of our greatest novelists emerges from her study. It happened again in 2014 when she wrote a short story called The Assassination of Margaret Thatcher, not a tactful title.

This time is no different. Today she stands accused of hating England and loathing Brexit voters after declaring she intends to become an Irish citizen. It’s time she handed back her damehood, her critics snap.

Mantel may be a mistress of precision over hundreds of pages, but she’s an ingenue in the headline wars of new digital media and its warring partisan armies. The truth about the Middleton speech was that Mantel felt sorry for Kate and for the royals in general. She ended with a plea to the media “to back off and not be brutes”.

Now she goes even further. “I’ve tried to sort of keep out of the Meghan thing because I think it’s far too soon to have an opinion. And anyway, all of us commentators are part of the problem. I’d like us all to say less. And let them have a chance to find some resolution.”

Royal Pains

Nobody — no journalist, no historian — has engaged more deeply with royalty than Mantel. With every character in her Wolf Hall trilogy of novels about Henry VIII and his chief minister Thomas Cromwell, she doesn’t simply like royals, love them or have opinions about them. She inhabits them.

So I ask her to inhabit Prince Charles. She proceeds to inhabit the Queen as well. “I’m very conscious that the present queen, and probably the Prince of Wales too, have a religious viewpoint on this; like the Tudors they believe God is watching them and they have to answer to God — not just as private people but as monarchs. That’s a spiritual burden and I think it ought to be thought about by all of us.

“He is a very deep thinking man and I am sure that includes thinking about his role and what it still means, even though he’d be a king in a modern world. Kingship is so ancient and it has a dimension of holiness.” She is no admirer of monarchy but she admires the devotion of Charles and the Queen. “I think they do it as well as anyone possibly could, take it as seriously as anyone could.”

How long does she think the royals have left? Her “back of the envelope” calculation is two generations. Poor old Prince George, I say. We both laugh. “I think it’s a fair prediction, but let’s say I wouldn’t put money on it. It’s very hard to understand the thinking behind the monarchy in the modern world when people are just seen as celebrities.”

She doesn’t find it hard to find the thinking behind Boris. “I think he thought being prime minister was going to be a lot more fun than it is. And that he’d cover himself in glory. When someone goes into politics they should calculate that the chances of emerging covered in glory as opposed to covered in mud are very small … I feel his grip on reality is a bit slippery.”

“I think they do it as well as anyone possibly could,” Mantel says of the Queen and the future King.

In her recent interview with La Repubblica she expressed something close to loathing for England, a washed-out place that “runs on the memory of power, but this resource is becoming exhausted”. She described Brexiteers as “smaller people — callow opportunists, insincere and devious and often ridiculous”.

This struck me as an outrageous thing to say about the millions who voted to leave, but now she backtracks a little. “I meant the Brexit politicians; I don’t mean the voters. I understand that there was a generalized discontent that people felt with government. I completely understand people’s dissatisfaction with their lives. But they located the blame in the wrong place.”

I ask if there is one thing she can think of that would improve Britain. “I’d like people to stop shouting and start listening to each other. I think in this country at this time it would be a change that could save us. We’re in a very bad place as regards public discourse.”

She is now planning to move to Ireland and eventually to take on Irish citizenship. Again she has said this is a response to Brexit and the state of England; again she backtracks. Her husband, Gerald McEwen, is an Irish citizen and her upbringing in Glossop was Catholic with Irish roots. “I shall need — under the present rules — three years’ residency … I don’t see it as walking out on this country. I am trying to see it as a creative act. I’m a person who’s always felt in transit. I think it’s a worthwhile experiment to close that loop and go back.”

“It’s very hard to understand the thinking behind the monarchy in the modern world when people are just seen as celebrities.”

They haven’t decided yet whether they will keep a base in England. Either way, I suggest, it’s a big, disruptive move for a 69-year-old with a terrible health record.

In her twenties Mantel became seriously ill. A psychiatrist concluded, bizarrely, that she was too ambitious and should stop writing. He prescribed antipsychotics that made matters worse — much worse. She avoided doctors thereafter and later accurately self-diagnosed. She had endometriosis. An operation left her “minus ovaries, womb, bits of bowel, bits of bladder”.

“Being the age I am now, I am a burnt-out case. It did a great deal of damage to my body and that’s never going to be mended.”

And she could not have children. “When your friends reach the grandmother stage you feel the loss of that as well. But it’s something I came to terms with a long time ago. It just means you have to find an original role for yourself.

“The things that happened to me earlier in my life have made me go to live in a very strange sort of body. And I’m constantly patching myself together. So I’ve been living in an experiment all these years, but there’s only me to conduct the experiment … I haven’t lived the life I’d have wanted.”

Does she, I ask tactlessly, support the legalization of assisted suicide? “I do. I worked in a hospital as a young woman and I accumulated some knowledge about dying, which leads me to that conclusion. Appropriate safeguards in place, of course. And I appreciate that legally it’s a very tricky area.”

Jewel in the Crown

But it is necessary to go beyond the controversies and the illness to make the really big point: Mantel is one of the greatest imaginative writers of our time. She never stops projecting herself into the mind of others — most dazzlingly in her portrayal of Thomas Cromwell. Historians flip-flop on Cromwell; he’s been a villain and a hero but these categories are frivolous compared with Mantel’s approach. She simply asks: what would I do in his position? With that simple question she has created the most believable Cromwell of them all.

The Wolf Hall novels ended last year with The Mirror & the Light. Like the first two books — Wolf Hall and Bring Up the Bodies — it is being turned into a stage play by the Royal Shakespeare Company. She has been involved with the adaptations before but this time she is the full-on co-writer with Ben Miles, the actor who plays Cromwell.

It is a sell-out. Its run has just been extended by eight weeks, probably helped by the enraged debate about her latest emergence. But the truth is that neither the English nor the world can get enough of this story of royal splendor and thuggery, of palace politics, of betrayals and beheadings.

I suggest it’s because the Tudors —notably Henry VIII and Elizabeth I — are just so damned intelligent. “Yes. That is true. Every member of that family is gifted. What unites them all is excellent brains. Monarchs are not renowned for that. When you come to the Hanoverians, well, there’s a great deterioration there.”

And what about Henry himself? In my head he is captured with just two words: brilliant and tyrant. But once again Mantel steps into his shoes and sees something much more real.

“People think he’s a monster, but he’s our monster. One minute you think you understand him, the next minute he’s off the scale. But I am very conscious that after 1536 he was in pain almost every day of his life. There’s a shame in the failing masculine body. He’s losing confidence in himself and it makes him lash out.”

“People think [Henry’s] a monster, but he’s our monster.”

Written as a novel, Mantel’s life story would be dismissed by critics as far-fetched. Born in Glossop, her early childhood was “happy and secure, and the platform I jumped off from, I think”. Then things turned strange. A new man, Jack Mantel, came to stay … and stay. Her mother was sleeping with both Jack and her father. “Then when I was 11 Jack took us off to another town. We changed our names to Mantel. But it wasn’t a new beginning because so many people knew what had happened.”

With McEwen she lived in some unexpected places — Botswana, Saudi Arabia. They divorced in 1981 in the midst of her medical crises. Something had changed. But then something changed back and they remarried in 1982. They are still together with homes in some entirely expected places - a place just outside London, and Budleigh Salterton in Devon.

In the course of all this she was quietly becoming a great writer. This became noisier when she won the Booker Prize for Wolf Hall and again for Bring Up the Bodies. It became clear she had, as one author put it to me, “created a new way of writing”. The first step to this new way was to write the trilogy in the present tense. “That came when I sat down to write the first paragraph. It was so cinematic,” she explains. “What I was seeing was Cromwell lying on the ground — well, I wasn’t seeing him; I was behind his eyes. So that settles things in 15 seconds. You’ve got the viewpoint and you’ve got the tense because when is it happening? Now.”

So Cromwell became both “he” and “I” because we read exactly what he’s thinking. This reaches a sensational climax in the last pages of the trilogy when we encounter the workings of Cromwell’s mind as he is beheaded. The effect of all this is to create a prose style that is contemporary but still makes you feel you are in the 16th century.

Will she now miss Cromwell? “Well, eventually. I’m working on a new novel so part of me is already moving on.”

Mantel is often said to have revitalized historical fiction. She has done much more than that. Like the great modernist writers — James Joyce, Joseph Conrad, Virginia Woolf — she has given us a new way of understanding the past and therefore the present.

At the end of the trilogy there’s a quotation from the great Italian poet Petrarch. “For you perhaps, if as I hope and wish you will live long after me, there will follow a better age. When the darkness is dispelled, our descendants will be able to walk back, into the pure radiance of the past.”

It is about Cromwell but on closer inspection is also about the woman who has inhabited him on our behalf.

The Mirror and the Light, based on the final volume of Hilary Mantel’s Thomas Cromwell trilogy, opens September 23 at the Gielgud Theatre, in London

Bryan Appleyard is a British journalist and the author of several books, including How to Live Forever or Die Trying