“I CAN BE a crabbit old bag,” declares Dame Harriet Walter, who fits neither description however much the lady doth protest. The distinguished, award-winning actress, writer and confounder of gender stereotypes, is charming, slender and elegant with the sort of striking high-cheekboned profile that ought to be stamped on a Roman coin.

No “old bag,” she. Walter, who was awarded a CBE in 2000 and a Damehood in 2011, may be on the cusp of “old age” and her 67th birthday – September 24 – but she is definitely not a grumpy old woman.

Age can not wither bone structure like her’s. And, certainly, custom can not stale her infinite variety. She has the distinction of being perhaps the first actress ever to play both the King and the Queen of England and has recently transmuted three of Shakespeare’s heroes into heroines in a celebrated all-female trilogy of his plays that became known as “the cell-block Shakespeare” -- the conceit being that Julius Caesar, Henry IV and The Tempest were being staged in a women’s prison.

“Actually, people think I’m crabbit when I’m not. It’s my face – I’ve never been beautiful, but I do think I’ve grown into my looks. I can look stern, although I often look serious even when I’m not,” she says with a dazzling smile when we discuss her latest book, Brutus and Other Heroines: Playing Shakespeare’s Roles for Women, which she will explore in an event at the Edinburgh International Book Festival.

We talk about being “a woman surprised by time,” short fuses and the fact that she was recently quoted as saying she almost cracked and ran away under the pressure of playing three Shakespeare roles in a day when the plays were performed back-to-back. “It was a joke, a throwaway remark -- and it became a headline,” she sighs.

We meet over coffee in Hammersmith, near the London home she shares with her husband, American actor Guy Paul, whom she married in 2011 when she was 60-years-old. It is her first marriage – her partner, the actor Peter Blythe, died of lung cancer in 2004. She was 52-years-old and she survived, she says, by following the advice of another Dame, Judi Dench, who told a mutual friend that after her husband’s death she “just put more of herself out there.”

Which is exactly what Walter did. As for her “serious” face, an innate ability to look effortlessly aloof on occasions has, of course, stood her in good stead throughout a long, acclaimed stage career in which she has been a star of the Royal Shakespeare Company (RSC).

Niece of the late actor Sir Christopher Lee, who famously created many blood-sucking monsters and villains on film, she is London-born and knew she wanted to act when she nine-years-old. She grew up in a fairly privileged, well-off family – one of her ancestors, John Walter, founded the Times newspaper – and she has been almost every Shakespearean heroine, from Ophelia to Beatrice and Helena, from Lady Macbeth to Portia and Cleopatra. Recently, though, she has inhabited Brutus, Henry IV and Prospero in that trio of ferociously staged, astonishingly acted, all-female productions for London’s Donmar Warehouse – Walter and the brilliant director Phyllida Lloyd’s riposte to what the New York Times has described as “theatrical manspreading.”

There have been many other major roles on stage in a career that has taken her from Joint Stock and John McGrath’s 7:84 in the 1970s to Ibsen, Chekhov Arthur Miller and Pinter. She was an electrifying, Tony-nominated Queen Elizabeth I in Schiller’s Mary Stuart – she met her husband during the Broadway run when he was playing a courtier. On television, she was the immensely grand Lady Shackleton in Downton Abbey, in which, according to one journalist, she matched that great Dame, Maggie Smith, arched eyebrow for arched eyebrow. More recently, she’s been a starchy martinet of a nun, Sister Ursula, in Call the Midwife, as well as Lady Clementine Churchill, wife to John Lithgow’s Sir Winston, in the Netflix series The Crown.

Her many films include Ang Lee’s Sense and Sensibility, Atonement and Star Wars Episode VII: the Force Awakens, and her latest movie is The Sense of an Ending, adapted from Julian Barnes’s Booker prizewinning novel. Currently working on three film and TV projects, she admits: “Honestly, I can’t complain. I am still getting some fantastic parts.”

She has written several books about acting and other subjects, including Macbeth: Actors on Shakespeare and an engaging, stylishly written memoir, Other People’s Shoes: Thoughts on Acting, in which she writes, “Acting is what I do with who I am.” Her book, Facing It: Reflections on Images of Older Women grew out of an exhibition she curated in Stratford-upon-Avon of photographs of older women who felt that after a certain age they had became invisible.

After a certain age, women certainly become invisible in Shakespeare’s plays. Still, she notes, running under the current of her own life has been the hum of Shakespeare. When she speaks his words she feels she’s “having a private conversation with a friend today who is whispering eternal truths in my ear.” She cannot imagine a world without him, but wishes he had put more women at the centre of his world/stage. “If only he would come back and do some rewrites!”

In Brutus and Other Heroines, she discusses the trajectory of her career through the Shakespearean heroines she has played as well as the male protagonists in the all-female trilogy. The book reads like an autobiography, I tell her.

“Perhaps it is a kind of autobiography. It’s a very personal journey and my growing ownership of the work. I think I was a late developer. I was rather obedient and did what people required of me. I delivered what was required. Early on, though, I embraced the feminist tendency so there was that narrative of not wanting to play into the super-bitch or the victim-female agenda. So I might have been much more famous if I had gone on following the set of rules that some men wanted me to [do] with those roles.

“As I write in the book, it is a journey from my thoughts as a 30-year-old who understood the vulnerability of Ophelia, gaining confidence and complexity through my thirties and forties with Helena, Viola, Portia and Lady Macbeth to a more relaxed, womanly Beatrice in my fifties.”

After she played Cleopatra opposite Patrick Stewart’s Anthony for the RSC in 2006, however, she remembers thinking, “Well, that’s it, I’ll have to pack it in.”

Where does an actress go after Cleopatra’s magnificent death? Aged mothers and family retainers perhaps? She has turned down several offers to play Gertrude to various Hamlets because she feels the character is even more “muzzled” than Ophelia. “Alright, there is Volumnia, or the Countess of Rousillon, Paulina is a possible, and there’s mad Margaret, but that is pretty well it, and none of them has the infinite variety of the Egyptian Queen. I felt I was just getting comfortable, that I had reached new heights – or plateaux even – with Cleopatra and now the road had run out.

“Then along came Phyllida Lloyd and her idea of an all-female Shakespeare season and an opportunity to engage our hearts and minds in things that were bigger than domestic issues and to celebrate and notice and not be coy about addressing gender imbalance.” It is a given anyway, she adds, that there is an imbalance of roles for women in theatre generally, yet she worried that taking on male roles might be seen as a vanity exercise. But, she writes, in her very coyness lay a revelation. “I had a typical female attitude. I didn’t feel entitled. We women can be as ambitious as men and as hungry, but then that old chestnut of needing to be liked rears its head.”

Early in Brutus and Other Heroines, she writes that when playing Helena in All’s Well That Ends Well she felt guilty about making the charmingly manipulative character as palatable as she could. “This tends to happen with actresses of my generation who do not want to play into any possible misogynist interpretation of a female role – that super-bitch thing again! We feel burdened by the need to overcompensate and make our character better than anyone else, wiser, more moral, more sympathetic, and that leads to a different, though understandable, kind of inaccuracy.”

Shakespeare has cast a long shadow over theatrical tradition, she believes. “The world has changed enormously since his day but the stories we tell about ourselves still tend to follow his template, with male protagonists whose thoughts and actions matter – and females who only matter in as much as they relate to those men.” Now, she feels that by playing men she is only following Shakespeare’s example. “It seems as legitimate for women to play men as it was for boys to play women.”

Her pale oval face lights up when I ask what it was like when she first tasted Brutus’s words. “Well, Shakespeare could never have imagined a woman could play Juliet or Cleopatra, say, so it was amazing to tackle issues he usually reserves for men, like horror, war, power and betrayal. For these three roles, I discovered that power comes from stillness, from not giving anything away. All the things that I tend to do as Harriet – hand gestures, speaking a good deal – all that, gone. It made me wonder why women feel the need to over-explain.

“The thing is in our productions we were never ‘aping’ men. We were instead showing how preposterous some male behaviour can be. The three plays also became a narrative about incarcerated women. I was not only playing Brutus, Henry IV and Prospero but an inmate called Hannah, who plays these parts. I based her on an American political prisoner after visiting a number of women’s prisons with Phyllida.”

Her inspiration was Judy Clark, who was imprisoned after her involvement in the Brinks robbery in 1981. She drove the getaway car. When Walter and Lloyd met her, there was no hope of her release, but her 75-year sentence was recently commuted. Like Clark, a huge majority of women in prison have not done anything violent, Walter points out. “By far the worst casualties are themselves and their families.”

In Brutus and Other Heroines, Walter writes about “channelling her inner Ray Winstone” and that walking onstage as a heroic heroine made her feel like a sixtysomething rock star. So who’s next? Hamlet? Coriolanus? Richard III?

“I would like to play Macbeth,” she confesses. “I’ve played Lady Macbeth and written about the play. I know it so well; I love it.”

Well, I tell her, I for one can not wait for her to rock the Thane of Cawdor.

Brutus and Other Heroines: Playing Shakespeare’s Roles for Women (Nick Hern Books, £12.99). Harriet Walter will be in conversation with Jackie McGlone at the Edinburgh Edinburgh International Book Festival on Sunday August 27.