The tenor in Elixir of Love called in with a sore throat. His understudy went missing and no-one else in the world had memorised the new street-cred English translation of Donizetti’s village comedy. So they flew in a Lithuanian who sang Italian to the rest of the cast’s English and the results were so exhilarating that the audience left begging for repeat performances.

Here’s how it worked. Edgaras Montvidas, tall and brooding, had an afternoon’s walk-through of the main stage business in Jonathan Miller’s new production of Elixir, set in a 1950s Texas hamlet with the guys in stetsons and the girls in Elvis frocks. Flouncing Adina, nicely trilled by Sarah Tynan, wore a Marilyn Monroe wig with obtruding rump to match.

It’s lunchtime at Adina’s Diner and the guys are chomping burgers in the noonday heat when Edgaras comes on and sings a lovesick Quanta e bella, silencing the room as you’d expect when a guy in blue overalls hits his notes like the young Lucy Pav.

After that, it gets really interesting. Edgaras clearly does not know which way to turn but he responds well to nudges from the chorus and is soon the thick of the action. Someone sings ‘Per che?’ and he responds, ‘per che? why not?’ It’s the kind of linguistic porridge you hear every day of the week on the top deck of a London bus.

On comes Andrew Shore as Dulcamara, dispensing quack potions. When Edgaras nurdles up for a bottle of pick-me-up, Shore – who has sung Dulcamara at the Met and is a brilliant comic actor – comes right back at him in Italian. ‘You speakka my lingo?’ says the look on Edgaras’s face, bringing the house down in mirth. Andrew plays him both ways, sometimes Italian, sometimes English. Everyone recognises this transaction. It’s the kind of Babel chat we have with Polish and Rumanian builders in our kitchens and Iraqi drivers in our minicabs.

The young Spanish conductor Pablo Heras-Cassado, very impressive in his first London run, manages to keep everyone on just about the same beat and when the curtain falls the eruption is louder than you hear on most first nights, the loudest cheers of all going to our brave, befuddled Lithuanian whose final clinch with Adina Tynan is so close and prolonged I thought it was going to take a fire-hose to prise them apart.

All in all, an unforgettable night at the opera – and one that has lessons for ENO which is stuck in a timewarp straitjacket of singing unnecessarily in English, when most of the audience can’t hear the words and are reading them off proscenium surtitles. It is not often nowadays that we see mixed opera casts singing in different languages, a situation that was common on many European stages until the 1980s. But the world has moved on and we live in polyglot cities. Why should opera not reflect the world around us and, in certain roles, allow plot confusion to be accentuated by a language gulf?

A Flying Dutchman in which everyone sang German except the sailor who sings in a Netherlandish dialect could be a distinct improvement. Katya Kabanova’s social isolation could be underlined by her singing Russian against the rest of the cast’s Czech. And why not, for heaven’s sake, not have a Carmen who sings gypsy Romish against a French and Spanish backdrop? I know quite a few singers who’d be keen to give it a go. Opera needs more thrills of the unexpected. ENO may have stumbled onto a gold mine.