10/01/2012 08:55 GMT | Updated 10/01/2012 09:08 GMT

Kate Middleton 'Boosts UK Economy By £1bn': Shoppers Copy Duchess Of Cambridge's Style (PICTURES)

Kate Middleton copycats are responsible for pumping more than £1billion into the British economy, it has been reported.

The newlywed, who celebrated her 30th birthday yesterday, is behind the boom which has seen the sales of certain tights, jewellery and dresses soaring.

According to The Sun, women are spending up to £250 each in a bid to look like the Duchess.

The leggy brunette’s style has proved so popular, consumer analysts Mintel even admitted their £1bn estimate is “conservative”.

Kate’s white engagement dress – the Nanette, by Reiss, sold out after the bride-to-be wore it for her official engagement pictures alongside Prince William.

The £159 dress was reissued in the US and the UK but sold out almost immediately.

The royal blue Zara dress she wore to face the media upon her engagement also flew off the shelves, as did imitations of the engagement ring Princess Diana once wore, which Kate now sports.

A trend for L.K. Bennett Sledge Courts followed, with Kate’s mother Carole and sister Pippa also getting in on the game, and sales of nude tights soared after being glimpsed on the legs of all three Middletons.

Lisa Bond, marketing director at fashion chain Peacocks, told a national newspaper: "The appeal of our new princess is turning the nation into Kate watchers."