Suddenly two dozen pairs of eyes are staring straight at me, the nearest of them only about six feet away. Two dozen voices emphatically deliver the words: “He must never, never know.”

All distinctly unnerving, but luckily it is nothing more sinister than the chorus of Garsington Opera rehearsing Offenbach’s La Périchole in a cavernous studio in East London.

At the helm is director Jeremy Sams, perhaps best known as a prolific translator of operas into English — and his translation of La Périchole is being used by Garsington.

How, I ask Jeremy as the rehearsal breaks for lunch, did he get into the very specialised translation business?

“I guess I’ve got a few of the qualifications. I’m a theatre person, and I grew up speaking a lot of foreign languages because I had an odd dad who was a linguist.

“He made me and my brother speak German one day, French the next, and even Italian as well. And I’m a musician, so all those things go together.

“But the trick of translating opera is not so much understanding the languages as fitting the words in with the music. It has to sound as if the words and the music are indissoluble, they have to cling together. That takes a lot of practice and a lot of goes.

“The other trick, of course, is rhyming, but that mustn’t draw attention to itself.”

But with Offenbach, isn’t there a risk of losing the seductive lure built into the French language when you move into English?

“The trick there is not to go dirty. Keep everything possible as a double meaning: French is much more on the money, whereas in English everything is bubbling underneath.

“Actually Offenbach himself, although his shows were very unbuttoned, he’d often set them in places that would be even more unbuttoned — in Ancient Greece or Rome, for instance, where the girls would be wearing not very much, and the boys even less.

“Or in the case of La Périchole it’s Peru — and that doesn’t necessarily mean a place in South America, it means somewhere so hot that you don’t wear very much.”

The storyline of La Périchole concerns two impoverished Peruvian street singers, and, at the other end of the social scale, a lecherous viceroy who will only take a married woman as a mistress.

“That was apparently a satire on Louis Napoleon in the Second Empire, who would also only have sex with married women,” Jeremy explains. “You couldn’t say that about someone in your own government, but you can say it about a viceroy in Peru, and everyone will know who you mean.”

Watching the rehearsal is Garsington Opera’s boss, general director Anthony Whitworth-Jones. He has overseen the company’s move from Garsington Manor eastwards towards the Buckinghamshire border, to a purpose-built pavilion on the Wormsley Estate.

And this year there is a new development: on July 1, La Périchole will be transmitted, live, to a very different location — Skegness Beach.

But this is his last season in charge, Anthony tells me.

“I just know it’s the right time to leave after seven years, for private as well as business reasons. I don’t want another executive position, where I am responsible for people, for money, and for the work on stage.

“After 40 years of executive responsibility, that I can do without. But, who knows, the odd project may come my way!”

Full details and tickets for the Garsington season call 01865 361636 or visit the website garsingtonopera.org