Britain’s Duchess of Cambridge has been credited with giving the UK economy a £1 billion boost after sales of her most popular wardrobe choices have risen.

Marketing experts have worked out that British women are spending an average of £250 a year to emulate Britain’s Prince William’s wife’s classic style.

Following the royal wedding in April 2011, females all over the UK have been copying the Duchess’ trademark fashion and beauty staples, including her bouncy blow-dries, nude tights and rich brunette hair colour.

Lisa Bond, marketing director at fashion chain Peacocks, says Catherine’s appeal is extraordinary.

"The appeal of our new princess is turning the nation into Kate watchers,” she told British newspaper The Sun.

British department stores and high street retailers have noted a rise in demand for similar or less expensive items Catherine has worn – including gems such as sapphires, dresses and feather fascinators.

Women across the UK have also been imitating the royal’s beauty rituals.

Eighteen per cent more girls are having £25 blow dries to copy the duchess’ "big hair".

And sales of chocolate brown hair dye are up 12 per cent at a well-known British drugstore chain.

Consumer analyst Alexandra Richmond explained why Catherine’s look is so enviable.

"Kate's look has something to appeal to everyone," she said.