Although Kat Stewart is well known for playing dark, in-your-face characters, her life experience has led her to a greater appreciation of hope and contentment. Her latest stage role is in Melbourne Theatre Company’s Heisenberg. “The idea I really love is that we spend all this energy trying to control our lives and take comfort in that … but we have very, very, very little control and what this play confronts you with is: What if that is not a bad thing?” By Peter Craven.

Actress Kat Stewart’s realms of possibility

Actress Kat Stewart, currently onstage in Melbourne Theatre Company’s Heisenberg.
Actress Kat Stewart, currently onstage in Melbourne Theatre Company’s Heisenberg.
Credit: Deryk McAlpin

Kat Stewart has played some of the grittier and more challenging roles about. You don’t get much darker or dirtier than Roberta Williams in Underbelly, the role that established Stewart in the public eye. Later she was the slippery, none-too-stable Nat in the very ambitious, very powerfully conceived Tangle, contributing massively to the sense of reality in that saga of upper-middle-class Melbourne life.

But Stewart is nothing if not versatile. At the most popular (and for a fair stretch enchanting) level, there was the sophisticated soap Offspring, in which she played the ditzy sister hitched to Eddie Perfect. On the Red Stitch stage in 2010 she did Strindberg’s Creditors as if she were wielding an axe of vengeance and rage. Her performance in Ayad Akhtar’s Disgraced, directed by Nadia Tass for the Melbourne Theatre Company in 2016, was integral to that production’s ability to bring a complex mainstream play to an Australian stage without yielding an inch of credibility from the American original. Her new TV show, Five Bedrooms, started on May 15 and she’s also doing a new play, Heisenberg. The latter is a two-hander by British playwright Simon Stephens about an American woman in her 40s, Georgie, and the relationship she establishes – if that’s the word – with an Irishman, Alex, who has seen threescore years and ten.

Heisenberg is a rom-com with a difference, as its title suggests – it’s named for the great physicist who formulated the uncertainty principle. “It can seem quite slight,” Stewart says. “But I think it’s greater than the sum of its parts … the way [Stephens] wrote it works to heighten just all that love and grief and hope and instability. There’s just so much going on and it’s an incredibly hopeful play.”

This shortish show – it runs without an interval and comes in at maybe 80 minutes – is a bit like a parody of a romantic comedy sketched out by Beckett in a facetious moment: a woman from New Jersey, who says she’s searching for her son, accosts an old Irish butcher in London.

In writing the play, Stephens was inspired by a principle from the treasure house of quantum physics, which arty types are inclined to appropriate and misapprehend. The received wisdom equates the uncertainty principle with the observer effect – that is, the process of observing something changes the thing observed. In fact, Heisenberg postulated that knowing a particle’s position made it less likely to know that particle’s momentum, and vice versa – in other words, uncertainty is built into the nature of things.

The notion of indeterminacy allows a playwright shading and colourful, distinctly audacious effects: arias about music, tango, great riffs that potentially bewilder a mind nursed on realism and expectation. But how does Stewart think all this indeterminacy stuff works in Stephens’ grave, funny, sometimes quite affecting play?

“What struck me when I first read the play,” she says, “was that I didn’t know what was going on from moment to moment, and I think it’s really important that if I do my job properly the audience should be genuinely wondering what’s going to happen at every surprising moment. And I think that’s the approach Simon took to writing the play. Obviously he had to know the basic thing that was happening, but he surprised himself in the way he wrote the characters and developed their exchanges.

“The idea I really love is that we spend all this energy trying to control our lives and take comfort in feeling that we have control of our lives, but we have very, very, very little control and the idea this play confronts you with is: What if that is not a bad thing? What if something potentially extraordinary comes from not knowing what could happen, what if that provides us with great freedom and brilliance?”

Stewart also loves that the play is a love story in weird clothing. “I love its oddness. They’re people who are not used to being with others. They’re kind of very offbeat people – they’re not that palatable in a lot of ways. And yet there’s a lack of judgement, they see something in each other and spark something in each other … There’s something fundamentally affirming about this play because it’s not sweet or saccharine. It speaks to what’s there in us as well as what we’re not.

“And I love a relationship being explored for characters who are over 39 – the age at which people fall off the cliff. These people who would be overlooked but still have so much to offer. In their own strange surprising way they’re really dynamic and the other thing is you don’t know if it’s going to work out or not. I suppose ideally no one knows if it’s going to be the greatest romance of all time or the greatest cautionary tale.”

It’s not hard to see how Stephens has taken Heisenberg’s uncertainty principle as a kind of loose datum for a play that represents a running reversal of a conventional set-up. Of course the principle may also function the way we tend to assume Yeats’s A Vision did – simply as the source of metaphors for his poetry. One suggestive possibility in the back of all this is that two postulates may be operative but only one can be followed through with. An old butcher given to elegant expressiveness of speech might nail down the truth about an improbable woman’s son or he might go on her quest with her, but can he do both?

A very different way of looking at Heisenberg is to see it through the lens of Christian notions of grace as they might be perceived by an addict, or indeed by anyone with a strong inclination to stuff up. A solution is impossible short of an act of grace, while an act of grace is the impossibility in which belief is invested. Heisenberg plays with this kind of uncertainty, this kind of rationality-defying sense of power and possibility.


Stewart was born a Catholic in Bairnsdale, in east Gippsland, in 1972. Her father was a solicitor and she went to a Catholic high school in the bush until she transferred to Melbourne, where her brothers were already boarding at Xavier. But she found herself at that Anglican establishment stronghold for “gels”, Merton Hall. She says she loves the ritual and tradition of the church but she’s not practising. What we hear in her account of this play she’s doing, though, over and over, is the yearning for what Yeats called a possible wisdom.

One of the most unusual things about Stewart, at least as a performer, is that not much of it seems to be about her. And running along with that there’s her desire to see the good in people, the good in things.

She’s always said that she loves playing bad characters, deluded characters, characters on the skids who chucked other people there, because people plunged in the mire are the people who require the greatest understanding. Something deep in this very likeable woman – with scarcely a strand of actorish extroversion in her – goes out to her spectacular mood swing of a character in Heisenberg, who wants an old man’s money or company or heart – or what?

“What I do like about my character,” Stewart says, “is that she’s got loads of attack, she’s so trenchant and she’s had a lot of grief in her life and she’s made a lot of mistakes. Through her efforts she has a tremendous effect on the character of Alex, who has tended to wrap himself up. At least she’s still swinging.”

You can tell that Stewart – and it’s implicit in all her years with Red Stitch, which her husband, David Whiteley, used to run – has a quiet resolve to do serious work, or at least to do serious work among other things. And she knows the importance of an actor’s craft and the necessity of staying in condition: “I really believe that if you stay away from theatre for too long, you lose your nerve. It’s certainly significantly challenging if you have a young family to do theatre. It’s not the easiest kind of balancing act.”

Seven years ago she had her son, Archie, and then in 2016, during the run of Disgraced, her daughter, Gigi (short for Georgia). She’s mellowed, she thinks. And she’s philosophical about the limitations of any Australian career.

“It’s not like you have much choice with this industry in this country, you can’t have a grand plan. It’s really what comes your way and you try to work with things that resonate with you… I want to play interesting characters in good scripts, really.”

She’s conscious, too, that marriage and motherhood have changed her perspective on the kind of dramatic material she might be attracted to or impelled towards.

“When I was younger,” she says, “I was thrilled to be doing lots of nasty in-your-face things and I enjoyed starker, intriguing, black material. But now, having lived a bit – and you lose loved ones – I have a real appreciation of hope… Tangle was a bit darker but even that was a celebration of and exploration of what a family means.”

So she wouldn’t be interested in playing Lady Macbeth, or Martha in Who’s Afraid of Virginia Woolf?

“With the right actor, yeah, I think that would be hard to turn down,” she says. “I’d probably jump at Who’s Afraid of Virginia Woolf? first though, because I’ve always loved it.”

And despite the palpable itch towards a more tranquil world view, she says she would not only happily do Chekhov – who perhaps represents the more tranquil side of desolation – but also Ibsen with his turbulence and desecration.

Her director in Heisenberg, Tom Healey, cast her 25-odd years ago in a National Theatre Drama School production of Angels in America, in which she played Harper – the young woman who’s married to the closeted gay lawyer. She’s still filled with gratitude, as if that long-ago obscure gig has been the greatest blessing in the world.

“It gives you so much,” she says. “Especially when you’re a young actor working out what it’s all about. The material elevates you and so do the people you’re working with. It’s so exciting to be working on such a rich piece. And I hadn’t come across Tony Kushner before; it was the first time and I found that electrifying.”

You feel in equal measure that Stewart’s happy to have been lucky and she knows she’s made her luck. She gives the impression of a woman who’s riding the river of possibilities, very self-possessed in her unassertive way about motherhood, family, something more than glory.

“The older I get the more I realise it’s not about preconceptions,” she says. “When you’re younger you’ve got an idea of what happiness looks like. The older I get the more I realise there are no steps to climb, there’s no more of ‘I’ll be happy when this happens’, it’s just about grabbing something with both hands and taking the moment right now … I want to keep growing and getting better and I want to keep working on really great projects with really great people. And that’s in and of itself enough for me. It’s enough for a happy and healthy family, and in terms of work I can’t ask for much more than that. And that’s a lot to ask for, actually.”

This article was first published in the print edition of The Saturday Paper on June 1, 2019 as "Realms of possibility".

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Peter Craven is a literary and culture critic.

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