Prince George gives a small Royal wave. Photo: Getty Images.
Prince George gives a small Royal wave. Photo: Getty Images.

The so-called "Kate Middleton" effect has been widely documented since the Duchess married Prince William in 2011.

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Anytime the brunette beauty steps out in public, her outfit is widely scrutinised, with fans scrambling to buy the same dress/coat/bag worn or carried by the Duchess.

Case in point: when Catherine left the hospital with Prince George yesterday, she caused the Jenny Packham website to crash.

Why? She was wearing one of the designer's dresses, an appropriate spotted blue design akin to the one Princess Diana wore when she left the hospital with Prince William 31 years ago.

Now the "Kate effect" seems to have worn off on Prince George, with mothers in the UK snapping up his baby blue swaddle blanket by the truckload. And in case you were wondering, yes, it's already sold out.

Those looking to buy the same dress as the Duchess will be disappointed as well to hear that it was made exclusively for her - the company has no plans to make it available for purchase according to the label's brand director, Blaire McColl.

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It's not the first time the Duchess has worn Jenny Packham. She's long been a fan of the British designer, often opting to wear her designs on the red carpet.

The Duchess wearing the already famous Jenny Packham blue spot dress. Photo: Getty Images.
The Duchess wore a dress by Jenny Packham to an event at Royal Albert Hall.