As the actors romp onto stage in Victorian era costumes, singing a boisterous Gilbert and Sullivan-style paean to England, the tone for the first act is immediately and hilariously established in Kip Williams’ brilliantly staged production of Caryl Churchill’s 1979 play Cloud Nine.

Josh McConville as Clive. Photograph © Daniel Boud

Churchill is a fascinating writer, combining a fierce intelligence with a playful, formal inventiveness, and though Cloud Nine was written nearly 40 years ago, and some of its observations are now somewhat outmoded, it still has plenty to say.

A study of sexual and identity politics, the play unfolds over two acts, which are not only wildly different in tone and style but separated by more than a century. The first act is set in Colonial Africa in the Victorian era and centres on a terribly British family headed by Clive (Josh McConville), a colonial administrator and pompous patriarch.

Churchill specifies that Clive’s coy wife Betty should be played by a man (Harry Greenwood), his nine-year old son Edward by a woman (Heather Mitchell), his daughter Victoria by a doll, and his black servant Joshua by a white actor (Matthew Backer). The household also includes Betty’s mother (Anita Hegh) and a governess (Kate Box) who is in love with Betty.

We meet them in troubled times. The “natives” are rioting, so a widowed neighbour called Mrs Saunders (Box) arrives to seek protection, as does a British explorer called Harry Bagley (Anthony Taufa). Betty fancies Harry and sets her cap at him, unaware that he is sexually involved with both Joshua and young Edward. When Clive discovers Betty’s attraction to Harry, he is incensed (“If I shot you every British man and woman in the world would applaud me”) – despite the fact that he is bonking Mrs Saunders.

Cloud NineHarry Greenwood and Josh McConville. Photograph © Daniel Boud

Churchill plays fast and loose with the comedy of manners genre in a satirical look at Victorian society, imperialism, exploitation, sexual oppression and gender politics, stirring in a broadly comic, Carry On like bawdiness – which Williams plays to the nines.

The second act is set in a London park in 1979. Three of the characters from Act I are featured – though they have only aged 25 years – along with four new characters. The actors playing Edward and Betty in Act I have now swapped roles. Edward (Greenwood) has been living with a gay man called Gerry (Backer) but when that relationship falters, he becomes involved in a ménage à trois with his unhappily married sister Victoria (Hegh) and her lesbian lover, a working class, single mother called Lin (Box) who has a young daughter (played by McConville). Betty, meanwhile, (now played by Mitchell) has left Clive and is in the process of discovering who she really is.

Though attitudes to sexuality have changed in the intervening century, and the characters enjoy considerable more freedom than in Act I, they are still constrained by society. As Victoria says: “You can’t separate fucking and economics.”

If the cross-gender, cross-actor casting sounds somewhat convoluted on paper, it is very easy to get your head around on stage and plays to the themes of the piece regarding gender and identity. Betty, for example, states that she is “a man’s creation”. As Churchill has said: “She wants to be what men want her to be… Betty does not value herself as a woman.”

Directing the play for Sydney Theatre Company, Williams stages his production on a cleverly conceived set designed by Elizabeth Gadsby. For the first act, the stage is covered with earth, on which stands a glass conservatory attached to the house (the rest of which we don’t see) and housing a grand piano. It looks completely out of place – a cultural edifice and beacon of civilisation dropped into an environment for which it is entirely unsuited. At the same time, it is a place where the family can shut themselves off from the world around them. It’s an eloquent image.

In the second act, the earth has been covered with grass, while miraculously quick scene changes that take place in darkness fill the conservatory with children’s toys one minute, and plants the next.

Heather Mitchell and Josh McConville. Photograph © Daniel Boud

Williams has gathered an exceptional cast who are all able to move between very different characters and performance styles with ease. Heather Mitchell is exquisite as the young Edward in Act I and the older Betty in Act II, playing with our heart strings in both roles. Her Edward is utterly convincing in his ungainliness as he shuffles from foot to foot, struggles to catch a ball, clenches his fists and walks at a purposeful clip when he’s angry, clings desperately to the doll his father forbids him to play with, and beams with delight at the prospect of time with Uncle Harry. It’s funny and touching and heartbreaking all at once and so well done that we accept him as a boy. Her older Betty is also a joy as she tentatively begins to explore her identity and new-found independence, free of her husband, and the final image of her on a swing leaves our heart soaring with her.

Josh McConville is pomposity itself as Clive, all terribly ‘what ho!’ and boorishly insensitive, a buffoon with power, lording it over his family and “the savages”. He’s also very funny as Lin’s five-year old daughter Cathy, though we’re more conscious of him as an adult playing at being a child than we are with Mitchell’s Edward. Harry Greenwood is funny yet moving as the fraught Betty who is constantly aflutter, and touching as the sweet, somewhat forlorn older Edward. Backer creates two keenly observed characters as the stiff, formal servant Joshua, who occasionally unleashes a bitter malice when Clive is nowhere in sight, and the gadabout, promiscuous Gerry. There are also excellent performances from Kate Box as the gung-ho Mrs Saunders, the kindly lesbian governess Ellen who yearns for Betty, and the working class Lin who is comfortable with who she is and what she wants; Anita Hegh as Betty’s stern mother and the intelligent but frazzled Victoria, and Anthony Taufa as Harry Bagley and Victoria’s condescending, manipulative husband Martin.

Heather Mitchell and Matthew Backer. Photograph @ Daniel Boud

Though the women and the gay and lesbian characters have more freedom and agency in the second act, times have changed since the 1970s and some of the sexual politics feel a bit dated. Nonetheless, Cloud Nine still resonates. The writing is fierce and funny, the satire scathing, and the dilemmas of the characters moving.

Williams’ passion for the play is evident and his production constantly hits the mark whether we’re laughing at the ribald comedy, gasping at some of the sentiments of the characters, or feeling their anguish. He and composer Chris Williams have interspersed the play with songs most effectively too. All in all, a wonderfully intelligent, stunningly staged production of an intriguing play.

Cloud Nine plays at Wharf 1 until August 12