What’s the connection between Harry Potter and Mozart? Fiona Shaw is perhaps best known these days as the boy wizard’s Aunt Petunia – or our greatest classical actress for those with longer memories. But for the past few years she’s been quietly building herself a reputation as an opera director, starting with the well-received but obscure Elegy for Young Lovers and Riders to the Sea for English National Opera. Now she’s tackling a cornerstone of the repertoire, Mozart’s Marriage of Figaro.

Written at the revolutionary cusp of the late 18th century, the opera’s tale of militant servants biting their master’s oppressive hand has often inspired a broadly social interpretation from directors. Shaw alights instead on its sexual politics and the interplay between love and power implicit in any relationship.

Her focus is Count Almaviva, part aristocrat and part animal in Roland Wood’s brutal and effective portrayal. Bleached steer skulls hang from the bare white walls of Peter McKintosh’s maze-shaped set like hunt trophies. Servants haul the carcass of a wild boar; villagers proffer their sacrificial tributes. The Count forces himself on his servants and ignores his loving wife, like a bull who needs to service every cow in the field.

But when the wronged women combine their wits, the Count’s animal instincts are no match for their feminine guile. The happy ending is more than a victory in the gender wars. It’s the triumph of civilisation over animal appetites. It’s social progress. The Countess starts the evening in 18th century corsets, but by the end she’s wearing the trousers – literally. She stands victorious in full modern dress while he’s down to his underpants.

It’s a well thought-out concept that would have worked better if there was more detail in the central roles and less fussy stage business from the non-singing extras. The set revolves to show us that the Count’s well-ordered household relies on the lower classes slaving away behind the scenes. But does that help the story, or is it just eye candy? Trite shadowy back projections are equally distracting.

If only Shaw had trusted the singers to carry the show. All are good. Elizabeth Llewellyn, filling in for the sick Kate Valentine with mere hours notice, is more than that. She was outstanding. Her physical and vocal poise elevated the Countess’s predicament to genuine tragedy. Rarely are the tears behind the stiff upper lip so beautifully and poignantly evoked. Her accomplice the American soprano Devon Guthrie was so sparky and assured as the ingenious servant Susanna that it was hard to believe she is barely out of music college. These two had no trouble carrying the show. It was clear from the start that no mere man would get the better of them.

Shaw’s production makes the wily servant Figaro himself less central than is often the case – the challenge to the Count comes from the women instead. Iain Paterson grew in stature as the night went on, aided by his impeccably clear enunciation of the English text. As the hopelessly hormonal teenagers, Mary Bevan’s inebriated Barbarina was a flirtatious foil to Kathryn Rudge’s hyperactive Cherubino. Superb comic support and not a hint of tired operatic caricature was provided by Lucy Schaufer’s lively Marcellina, Jonathan Best’s pompous Doctor Bartolo and Timothy Robinson’s wheedling Don Basilio.

Former ENO music director Paul Daniel returned to the pit to supervise a beautifully balanced account of the score just lacking that final degree of sparkle.