Helen Mirren won an Oscar for playing the Queen on the big screen, and now critics have hailed her reprise of the role on the West End stage.
Reviews have described Dame Helen's performance in new play The Audience as "magnificent".
The play imagines the private meetings between Queen Elizabeth II and her prime ministers over her 60 year reign.
Directed by Stephen Daldry, the play runs at the Gielgud Theatre until 15 June.
Among the audience at Tuesday's opening night were Sir David Frost, politician David Miliband, film director Tom Hooper and actresses Sheila Hancock and Gemma Arterton.
The Audience reunites Dame Helen with playwright Peter Morgan, who also wrote 2006 film The Queen.
The cast includes Haydn Gwynne as Baroness Thatcher, Edward Fox as Sir Winston Churchill, Paul Ritter as John Major and Richard McCabe as Harold Wilson.
In one comic scene, Mirren's monarch falls asleep during a meeting with David Cameron (Rufus Wright). There are also up-to-date references to the Pope's resignation.
Throughout the play, the older Queen converses with her 11-year-old self, a role played by three child actors throughout the run. There are also some scene-stealing appearances by real Corgis.
In his five star review, the Daily Telegraph's Charles Spencer lavished praise on Morgan's script.
"In this marvellous piece, with Helen Mirren once again giving a magnificent performance as the Queen, he penetrates at least some of her mystery, with compassion, grace, affection and humour."
Another five-star review from Whatsonstage.com's Michael Coveney, noted the play's "imaginative range, lack of sentimentality and incisive intelligence".
"But the most striking structural device," he said, "is that of pairing Mirren with her younger self (Nell Williams on opening night) as both a voice of conscience and a receptacle of the older Queen's wisdom and advice."
Morgan presents the Queen's encounters with her prime ministers in non-chronological order, and most reviewers marvelled at Dame Helen's transitions between the monarch's older and younger selves.
"The 67-year-old Mirren rises to the daunting technical challenge with a quite uncannily fluid lightness of touch as she shifts back and forth on an age-spectrum of six decades," wrote The Independent's Paul Taylor.
"At one end, in mourning black and with a tight, high-pitched plumminess of voice, she's the 26-year-old neophyte, already angling to secure her interests as a wife and mother against the paternalist and patronising solicitude of Churchill... at the other, she's an octogenarian, nodding off during a session with the bland Cameron."
He concluded: "Mirren's tartly humorous and profoundly human portrayal of a woman who is, by nature and nurture, about as touchy-feely as she is Roman Catholic although required to be, by turns, sounding-board, confessor and therapist, is magnificent."
But The Guardian's Michael Billington was less convinced by the play's format. "However hard Morgan tries, the evening can't help but seem like a series of revue sketches: a kind of 1956 And All That," he wrote in his three-star review.
"What holds it together is Stephen Daldry's adroit production and Helen Mirren's luminous performance, which, even in a non-linear script, pins down the Queen's steady growth in confidence and authority."
The Audience will be broadcast live to cinemas on 13 June.