Standards have been set when it comes to golden couples of stage and screen. Half a century ago, when Elizabeth Taylor and Richard Burton met on the set of Cleopatra, then the most expensive movie ever made, the powerful personal chemistry was immediately clear. In consequence, the love of the two British-born stars is now almost as fabled as the story of Antony and Cleopatra itself.
Since the 1960s there have been occasional challenges, one from Kenneth Branagh and Emma Thompson, perhaps, for the title of Britain's premiere theatrical partners. But quietly, even reluctantly, since they do not desire it, a talented new pairing has staked a claim: Anne-Marie Duff and her husband James McAvoy.
Their screen union did not involve burnished Egyptian barges and a cast of thousands. Instead it took place in a kitchen on the fictional Chatsworth council estate where, as the unlikely lovers Fiona and Steve in Channel 4's Shameless, they made passionate love for the television cameras against a Formica worktop.
This weekend that impromptu coupling seems in the distant past, as McAvoy stars as Macbeth on the London stage, while one of his three new films opens in cinemas across Britain, and Duff prepares to appear as Nina in Eugene O'Neill's Strange Interlude at the National Theatre.
Duff still maintains the kitchen scene was no fun to shoot, even though she liked McAvoy. "It is like sumo wrestling in knickers in front of a group of strangers," she has claimed.
For Emma Burge, who brought the two together as producer of the first series of Shameless, the memory of watching them work in the early days is a fond one. "There was a very sweet kind of spark and a rather nice, but slightly charged feeling about the place," she recalled this weekend.
Duff is to return to Chatsworth to say goodbye in the final episode of Shameless this May. It is something she always said she would do for a show that made her name and earned her a Bafta nomination by casting her, aged 33, as a 20-year-old forced into caring for her young siblings. "We thought it was a dark drama and didn't get the comedy at all. For some strange reason none of us sniffed that out. I thought it was brilliant and clever, but we were all like pioneers. We didn't really know what we were doing as there had been nothing akin to it," she has said of screenwriter Paul Abbott's creation.
Duff had already appeared on stage opposite Helen Mirren in Collected Stories, picking up an Olivier nomination. Burge said: "I had seen her in a play with Mirren and I remembered this very young-looking person. Her agent then told me that Anne-Marie was a little older than she looked. And since we wanted our Fiona to have an age on her because of the responsibility of bringing up a family, we wanted to see her. We all utterly fell in love with the idea of having her as our family's surrogate mum."
Since she and McAvoy left the acclaimed show in 2005 their careers have gained incredible weight, substance and variety. McAvoy's physically rigorous Macbeth at the Trafalgar Studios has been much-admired this spring and last Friday his new thriller, Welcome to the Punch, co-starring Mark Strong, was released. Next up is Filth, based on the Irvine Welsh novel, then comes Danny Boyle's Trance. And on Saturday he starred alongside Benedict Cumberbatch in Radio 4's production of Neil Gaiman's Neverwhere, originally filmed as a BBC TV series starring Gary Bakewell in 1996.
"I am really thrilled by what has happened for them," said Burge, "but not remotely surprised because they have incredible capacity. They both have a core energy and very quick minds and they are effortlessly able to sum up the human condition."
Despite their success, the couple continue to live in a north London flat with their son, Brendan, who was born in 2010 and named after Duff's father. Neither grew up in the area. McAvoy, 33, is Glaswegian and 42-year-old Duff, who is of Irish descent, grew up in Hayes, Middlesex, the daughter of a painter and decorator and a mother, Mary, who worked in a shoe shop. Friends say they like the area and will not live in Hollywood full time.
Duff has concentrated on theatre work since Shameless, with triumphs as St Joan at the National Theatre and in Rattigan's Cause Célèbre, but she came back to television drama last year to give an unsettling cameo performance in the BBC's Parade's End and was one half of a superb pair of performances alongside Olivia Colman in Jimmy McGovern's Accused.
Both McAvoy and Duff have faces that suggest youthful innocence, something which makes the subtlety and range of the parts they play all the more unexpected. Although McAvoy quickly distinguished himself on screen in Atonement and The Last King of Scotland, he is now also a Hollywood action hero, starring in Wanted and as a young Charles Xavier in X-Men: First Class. His friend James Corden has noted approvingly the way McAvoy balances his work between mass entertainment and independent cinema. "You can see in his career there is a sense of 'one for me, then one for them', one project to keep the bigger picture happy, Wanted, or X-Men, and then one to feed the soul," he has said.
Yet McAvoy is also happy to try on a cosier persona too: voicing the animation Arthur Christmas, playing the faun Mr Tumnus in The Lion, the Witch and the Wardrobe, bearing the Olympic torch through Glasgow or doing a bit of Red Nose posing.
Burge wants to speak up for the big screen blockbuster parts too. "To really pull off an action movie is an incredible skill and I don't think people realise that," she said. If a slight figure can make action, or violence, credible on screen, it is due to his vitality, she suspects. "When he came on to the Shameless set for the first time he had this amazing physical presence, I remember."
The couple have vowed not to speak about each other publicly, but McAvoy makes it evident that he thinks his wife has the real gift for theatre – an ability to commit totally. Director Howard Davies spotted the same abandoned quality, once saying: "She throws herself at parts as if bruising herself on them."
In spite of his film-star status, McAvoy suggests it is stage performance he prefers. Film, he has argued, always means that "the world will have changed by the time the audience sees it". He loves the immediacy of theatre and the fact "you tell a story from beginning to end and never stop".
His Macbeth for director Jamie Lloyd has been praised for its fully fledged assault on the expectations of the audience. "James's instinct is such that he'll throw himself into it 100% each time we do it. There's no skirting around the edges," Lloyd said recently.
McAvoy puts it more plainly. "I am a very shouty Macbeth. You know you've got the audience there and can do anything to make them feel uncomfortable. We do it on purpose."
His whole-hearted portrayal of the ambitious Scottish king has been reflected in the number of injuries sustained in the run. "We got cuts and bruises all over and we are down at the physio a couple of times a week," he has revealed, admitting it will be a struggle to get through to the end of April when the show closes.
He grew up in Drumchapel, Glasgow, in the care of his maternal grandparents and with his sister, the actor Joy McAvoy. His parents divorced when he was seven and his mother, Elizabeth, a nurse, judged that the children would have a more stable childhood there. He left drama school in Scotland in 2000 and by the time he appeared in Shameless he had already starred in the 2003 TV series of State of Play and was lined up to play the nerdy lead opposite Rebecca Hall in a film comedy about a quiz team.
"When we made Starter for 10 James was near the start of his film career, yet already he was a natural on screen," said the film's producer Pippa Harris. "One of his great strengths is his versatility – for us he played a charming, gauche university student, but he's just as believable wielding a gun in Welcome to the Punch."
McAvoy is now Hollywood-bound once more, making The Disappearance of Eleanor Rigby, a film drama in two parts, with Jessica Chastain.
Arguably, given their surnames and McAvoy's recent appearance in Macbeth, if we must have Brangelina, perhaps we can now adopt MacDuff as a composite name for the couple. And, since the Shakespearean phrase is actually misquoted and then corrected in the BBC's production of Gaiman's Neverwhere this weekend, we do perhaps have licence, just this once, to cry out: "Lay on, MacDuff!"
• This article was amended on 17 March 2013. The original version said Anne-Marie Duff was preparing to appear as Racine's Berenice; in fact that production was last year.
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