Kate Middleton and Prince William on the day they announced their engagement

Kate Middleton became one of the most watched women in the world back in 2010 when she and her long-term partner Prince William decided to take their relationship to the next level and gave us the most exciting royal wedding since, well, the '80s. 

Of course, Kate had always been a topic of fascination for the British public, who had seen their romance grow from their early days at St. Andrews University in Scotland. However, for the rest of the world, their engagement was the start of the undisputed Middleton mania that began, and continues to, surround Kate. 

So, it's no wonder that the dress she chose to wear to announce their engagement has since become her most iconic look to date (bar her stunning Alexander McQueen wedding dress, obv). 

Kate Middleton and Prince William on their wedding day in April 2011

We probably don't need to remind you that her dress of choice — designed by one of her now go-to labels, Issa — was an instant hit on the fashion scene and proceeded to sell out literally moments after the official photographs of the engaged couple hit the Internet. And since the 'Kate Effect' struck almost FIVE YEARS AGO (we know, where has the time gone?!), it hasn't been restocked. That was, until now... 

Style emporium Harvey Nichols took to its Twitter page to reveal that it will exclusively stock the now world famous 'Phylis' dress for the first time since it sold out all those years ago. The tweet read, 'First seen on the Duchess of Cambridge, @IssaLondon's Phylis dress tops our wish lists.' Ours too, Harvey Nichols — and we're sure we're not the only ones. 

Since Kate was catapulted into the media spotlight in November 2010, everything the Duchess wears continually sells out moments after the designer or label is revealed, and the Kate Effect is showing no signs of slowing down. In fact, it may just be hereditary — her son, Prince George, sparked an influx in the sales of Crocs shoes when he wore them to watch his royal father partake in the polo last month, and her newborn baby daughter Princess Charlotte's blanket which she was wrapped in to leave the hospital proceeded to sell out as well. In short, if you want to get your hands on anything this adorable family wears, you better move fast.

Kate's iconic Issa dress is on sale now for £575 and is being stocked in sizes 8-14, meaning more of us can get in on her royal style than ever. Even if it's been five years in the making...

Continued below...

Look back at Kate Middleton's best ever outfits and fashion choices with our homage to her style.