Short and shapely, she sits unaccompanied in a London hotel lounge, suitcase at her side. She’s on her way home to the Channel Islands, but offers coffee and a tentative smile before sinking back into the sofa and expressing apprehension at the prospect of giving an interview. Actually, it’s more the photos than the questions, she says, with a twinkle in her eye.

Perkins, a youthful-looking 61, is disarmingly chatty — not what you would expect from a woman who has dodged the spotlight for so long.

Working with her husband Doug, she founded the Specsavers optical chain 21 years ago, and has since built it into the biggest privately-owned chain of opticians in Europe. It has 15,000 employees, 900 optician partners, with no debt, no investors and a value probably running into hundreds of millions of pounds.

But while Specsavers’ advertising is seemingly ubiquitous, optician’s daughter Mary and policeman’s son Doug are as low-profile as can be. Neither likes giving interviews, nor — because of Specsavers’ Guernsey base — are their company accounts quite as transparent as those of mainland firms.

Exactly how much money they make on the business’s estimated £750m turnover, or indeed how much that business is worth, remains the subject of speculation.

But here she is on the hotel sofa, telling me to ask anything I want.

“Actually we don't take a salary,” she beams, amused at my curiosity. “We live off the interest on our original investments.”

Those investments were bought with the proceeds of their first business success: a chain of opticians set up around Bristol in the 1960s, then sold for £2m in 1980.

The couple, who met at university when training to be opticians, moved to Guernsey, where Mary Perkins’s father had retired. By 1984 they were bored, and plunged back into the market with Specsavers.

Since then the chain has become one of the great retail success stories of the past two decades.

Capitalising on new laws allowing opticians to advertise, and using a joint-venture system that allows individual opticians to keep profits while paying a management fee to Specsavers, the Perkinses have revolutionised a previously crusty profession.

But the difference between them and other retail entrepreneurs is that, so far, Mary and Doug have shown no sign of ceding an iota of control to anyone else, or cashing in even as they approach bus-pass age.

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