YOU can call Waitrose many things, but don’t even think of tagging it the posh person’s supermarket.

“No, I do object to that,” says Steven Esom, Waitrose’s baby-faced managing director. “We are not posh people and, look, this isn’t exactly swanky, is it?”

He gestures round his modest fourth-floor office overlooking the Waitrose lorry sheds at the supermarket’s base in Bracknell, Berkshire. In the distance, there is some leafy green. More directly visible is the sprawling industrial estate on all sides, baking in the summer heat. “When visitors can’t think of anything to say to me, they go, ‘um, nice view...’”

Esom gives a cherubic smile. Despite the heat and the fact that his building’s air conditioning has packed up yet again, his sense of humour is buoyant. Shortly before, he had managed to biff himself on the nose, restarting an old nose bleed — the legacy of a ball in the face during a kickabout with his five-year-old son — and calmly shrugged it off mid-interview. That’s composure.

On the wall beside him, a map of Britain is dotted with pins showing the positions of the 144 Waitrose stores that swarm over the bottom half of England. Look carefully and you might see another 19 stores further north, recently purchased from Morrison Supermarkets — an acquisition cleared by the Office of Fair Trading this month.

That sale was forced on Morrisons by regulators after its purchase of Safeway. For Waitrose, the 19 new stores (bought for an undisclosed price) offer a leap in size and coverage that must leave Esom believing all his Christmases have come at once. A scarcity of sites and stricter planning regimes have made it hard to open new stores. Suddenly opportunity beckons.

“The new stores will take us from sales of £2.7 billion to £3.3 billion in 18 months,” says Esom. Over the next five to ten years, he adds, Waitrose’s size will double, part of a confident approach to building its niche as a food specialist supermarket. And that is in a battleground where ever-bigger competitors are constantly widening their product range and slugging it out to the death.

Perhaps it pays to be different. Esom, at 43 a generation younger than most supermarket bosses, has headed Waitrose for two years. Medium-height, chunky — “I have to work hard at keeping my weight down” — and looking more like the head of the sixth form than managing director of one of Britain’s best-known stores, he carries a reputation in the industry as a good relationship-builder and efficient moderniser.

He is also known to be somewhat press-shy. As a former J Sainsbury high-flyer, he has kept a discreet silence on the problems afflicting his old employer. Others say the silence speaks volumes. “Esom is the torchbearer of everything Sainsbury used to stand for,” says CSFB analyst Tony Shiret, “except that he is doing it at Waitrose.”

But if Esom is reticent about rivals, he is less so about Waitrose. A confident talker, with a nice line in understatement, he says he likes to introduce himself to rival bosses as a “niche regional grocer”.

“I think they are finding it less and less funny,” he says. He has a point. Waitrose, part of Britain’s biggest employee-owned co-operative, the £5.1 billion turnover John Lewis Partnership, has been outperforming many plc rivals.

But its partnership status — Waitrose is owned by its 30,000 employees — was supposed to be a disadvantage, making it tougher for the business to raise funds for expansion and harder for its management to boost profits. Not any more, says Esom. John Lewis raises capital through bonds that the City is keen to buy, and it runs its supermarket business on the same metrics as any rival company.

As for ownership, it is now a selling point. “People are more interested in who they spend their money with. They want to know what they stand for, and I think we want to emphasise that we are different.”