The billionaire couple you've never heard of

They're the eighth richest couple in Britain, with more money than the Beckhams - but the chances are you'd never recognise them in the street.

According to the Sunday Times Rich List, Douglas and Dame Mary Perkins saw their wealth rise by £50 million last year to a grand total of £1.6 billion. That makes them nearly three times richer than the Queen.

However, Dame Mary tends to shop on the high street, and drove her last car for 12 years.

"We don't move in rich circles, none of our friends have second properties or jet-set lifestyles so it's never occurred to us to live in any other way," she commented in one interview.

The couple rarely go on holiday, and still live in the four-bedroom house in Guernsey that they bought more than 30 years ago.

And it was in a bedroom at that house that she and Douglas founded the firm that made their fortune - Specsavers, the world's largest optical chain.

See also: The world's five richest people

See also: A new richest man in the world - for just two days

The couple met on their first day at Cardiff University, where they were both studying optometry. When they graduated, they borrowed some money from Douglas's grandmother to buy the optician firm owned by Mary's father.

And the business went from strength to strength, expending to 23 outlets. In 1980, the couple sold out for £2 million to a company that was later bought by Dollond & Aitchison.

That might have been enough for most people. But when, in 1984, opticians were given permission to market direct to the public, Mary and Doug spotted up an opportunity. Working on a table-tennis table in the spare bedroom, the couple created Specsavers.

Specsavers now has more than 1,800 branches in the UK and abroad. It has 40% of the British market, where it sells 12 million frames a year in more than 1,000 styles and colours.

And while still running the business, Dame Mary also manages to find time for charity work - one of the reasons for her Damehood. She supports Age Concern and Women's Refuge, for example, as well as several local organisations.

"Life has been so good to me," she says.