As a girl who is constantly trawling the internet for the latest shoes, dresses, handbags, shoes, makeup, jewellery…oh, and did I mention shoes? It’s difficult not get caught up in the latest fashion craze that is Kate Middleton.

In the last few months the new Duchess of Cambridge has become one of the most famous women in the world and a major fashion icon, sending shoppers into a frenzy both online and in-stores.

The new flavour of the week- a Reiss “Shola” bandage dress that the Duchess wore to meet the Obamas sold out within hours. When photos emerged online of the Duchess wearing the dress, priced at £175, traffic to Reiss’ online store spiked to a massive 500% with one dress selling every minute! The demand was so high from women desperate to copy Kate’s style that the surge of traffic caused the site to crash.

The results of this have had a last effect for the Reiss brand with traffic remaining up by 200% two weeks after the dress was worn. This goes to show the inspiration Kate has sparked in the mind of consumers equalling massive FREE publicity for Reiss, all from a simple PR shot of her in the dress.

It’s not just Reiss that is benefiting from the ‘Kate-Factor’ the Duchess has been sporting many high street names including LK Bennett, Links of London and her favourite brand Issa.

The demand for Kate’s style has been so high that cheaper ‘repli-Kates’ have been designed by value brands including Tesco and Matalan and surprise, surprise, having the same sell-out effect.

We all know, celebrity sells. That’s why so many brands out there attach a famous face to their name, think Cheryl Cole: L’Oreal, Twiggy: Marks and Spencer, Kiera Knightley: Chanel and Emma Watson: Burberry. But no-one has had this effect on our fashion choices since, well Princess Diana.

How can a single photo of one person cause websites to crash; stores to sell out in an instant and fights to break out between hysterical women over the last pair of earrings worn in an engagement photo?

Perhaps, the great thing about Kate is that the items she wears are attainable for us mere mortals. Perhaps  we just can’t help ourselves!

There’s definitely a welcome element of escapism and make-believe. Just like when we dressed up as a princess as  little girls, some of us take this ‘dress up’ into our adult lives by emulating  a real princess’ style and, in a sense, entering Kate’s world.

Tamara Mellon, owner of celebrity shoe brand Jimmy Choo says  “When you buy shoes, it is like buying a little piece of fantasy, a bit of escapism. It is the fantasy of my lifestyle–the helicopters, the marriage, the cars my husband owns, the fantasy fairy-tale elements of my life.”

So is all this copy Kat-ing good? Well it is for UK brands.

Everything the Duchess has worn so far has been by British designers and they have benefited greatly from her choices, providing an abundance of free publicity and brand awareness not just in the UK but internationally. According to research commissioned by Marketing Week brands chosen by the Duchess need to maximise their PR and social media to publicise this Royal association and get the most out of it.

Public fascination with the Royal family has a long history, which is why increased opportunities to glimpse into their lives means that people can get even closer to their idols and spend considerable amounts of £££’s doing so.

With no sign of the ‘Kate-Factor’ slowing, the Duchess will undoubtedly continue to have an effect on brand desire for a considerable time to come – and you can’t put a value on that.