From Kate Middleton To Sarah Jessica Parker, Why Is This Polka Dot Dress So Popular?

Not copying another woman's dress is one of those iron-clad rules supposedly written into the lore of female friendship (also in this category: dating an ex, posting the picture in which you look amazing but your friend looks like Ozzy Osbourne).

But there are always exceptions to the rule, and every now and then an item of clothing lands in our lives which makes a bit of fashion doppelganger-ing necessary. The latest of these legendary wardrobe staples? Kate Middleton's floor-sweeping Alessandra Rich polka dot dress, which she wore for the official portrait for Prince Charles's 70th birthday, and then again this week for a 75th D-Day anniversary.

Perhaps its the summer-trending polka dots, perhaps it's the fact that it's loose fit means you can comfortably raid the buffet (always a very important element of any summer dress) but for whatever reason, we've all fallen in love.

We're not the only ones either: the now sold-out dress has become a firm favourite with celebrities, politicians and royals alike (its fans include Sarah Jessica Parker and Daisy Ridley). And Kate Middleton isn't the only one to wear it in a royal context, either – the dress was worn by Abigail Spencer to Meghan Markle and Prince Harry's wedding.

So what's all the hype about? Grazia's fashion news and features director, Laura Jordan says "'I think it manages to achieve that perfect but rare balance of being flattering (the silhouette), timeless (a polka dot dress is a classic) and just the right amount of ‘fashion’ (the exaggerated collar). It’s versatile – that modest cut is perfect for weddings and tricky formal occasions, without being stuffy.

'I find a lot women feel more comfortable covering up, Alessandra Rich’s dresses are a masterclass in being able to do that without looking frumpy. I love the slightly ‘80s, Sloaney air to this dress. Can’t you just imagine Princess Diana wearing it back in the day?'

While the dress has now completely sold out, there are some excellent (and more affordable) accessories from Alessandra Rich – the gargantuan crystal earrings and hairbows, in particular, are worth a look.

In the meantime - check out all of the celebrities who've fallen for the charms of the now-legendary dress. Copying your friend has officially never been so chic...