Playground was premiered at the 1979 Edinburgh Festival in a triple bill with Concerto and Elite Syncopations. The ballet is a social parable, which can initially leave its audiences with a sense of dislocation. It is not immediately clear if the characters seen on stage are children playing adults or adults playing children. It is the latter; the playground of the title is an asylum. MacMillan, who for several years had been undergoing psychoanalysis, is questioning where the balance of madness and sanity lies. In a mad world, he might be suggesting, the sane may appear mad.

As on several previous occasions, MacMillan began work with the Orpheus myth as a guide. Over the weeks of rehearsal Orpheus mutated into an intruder at a mental hospital. Yolanda Sonnabend’s wire-meshed courtyard is more suggestive of a prison than of a playground. Its inmates are adults acting out fantasies of childhood. For some, adults playing at children playing at adults, their fantasies are multiplied over as if in a hall of mirrors.

The intruder, a young man, becomes involved with the young woman, the Eurydice figure. As their encounter intensifies, she has an epileptic fit. The ‘vicar’ begins to pronounce funeral rites over her ‘dead’ body; the young man becomes violent and is attacked by the patients. He is then carried away in a straitjacket by hospital attendants (if so they be). The patients remove their children’s clothes and file off in drab institutional garb. The young man - a MacMillan outsider figure? - is left along banging his head against a wire fence.

Mary Clarke, writing in The Guardian, thought Playground “a mighty powerful piece of theatre, (using) a sparse vocabulary of movement with tremendous effect.” To Clement Crisp of The Financial Times Playground was both heart-rending and disquieting: “MacMillan’s style owes something to the manner of his My Brother, My Sisters, but Playground is even darker in mood though warmed by a compassion for the derelicts it studies. The reverberance of the characters and their relationships makes the piece far superior to any mere observation of madness.”

Twelve years later, in an interview with John Drummond for BBC Radio 3’s Third Ear, MacMillan acknowledged that Playground drew on his own distressed memories of his mother and her proneness to epilepsy. MacMillan admitted privately to Clement Crisp that it was a piece that he would liked to have seen performed by Pina Bausch’s Dance Theatre of Wuppertal.

• First performance: Big Top, Edinburgh Festival, 24 August 1979

• Company: Sadler’s Wells Ballet

• Cast: Marion Tait, Desmond Kelly, Stephen Wicks, Judith Rowann

• Music: Gordon Crosse

• Design: Yolanda Sonnabend

• Benesh notation score: Grant Coyle (1979) Working score.