I must've been doing my A Levels when the very first Topshop opened up in Hong Kong and people lost their collective minds. Before that, it was just this mythical inaccessible brand that people who went on a British holiday would come back showing off. Now I've moved to the UK, it's lost that special sheen a little but is no less one of the first stops I make on a shopping trip to find gems - like this Topshop polka dot dress. I saw it online, then went to try it on in person one day because I couldn't stop thinking about it and spent a week umm-ing and ahh-ing over it since it was out of my price range. (Spoiler: I bought it.)

It's currently totally sold out and going for triple the original price on eBay. It's so popular that Marie Claire and The Sun - boo, hiss - and a bunch of other publications have done news stories JUST ON THE DRESS. At one point, the dress was retailing for as high as £200 on eBay. I paid £49, for reference.

It got me thinking, why do some high street pieces go like hotcakes and others just die a slow death in the sale section? Well, I had a little think and have three theories. Also heads up: this dress really needed to be ironed.

1. The zeitgeist wants what the zeitgeist wants.

It is impossible to get away from polka dots at the moment. The reign of the polkadot started at fashion week when Dior, Valentino and BALENCIAGA had everyone seeing spots, it's been trickling down ever since into the high street. Literally every shop you walk into (Topshop aside) has the print and Instagram is just awash with different colours - the most popular being white, black, brown and red.

Mixed prints have also been a big and somewhat daunting trend that's surfaced this year. Rixo London literally exploded onto the scene with their chaotic colourful dresses, however they're not for the faint of heart. I think the reason this Topshop dress does so well is because it manages to play into that trend by mixing two differently sized polka dot prints - making the dress interesting, but not too interesting if you get my drift.

2) But the zeitgeist also wants something nostalgic.

I have this wild theory that the royal wedding has everyone in a nostalgic mood, especially since there's been a lot of coverage regarding Princess Diana, with tributes to her at the wedding and so on. Heck, I even had to write a story the other day at work about how she still remains the most influential royal fashion icon of all time. And well, Princess Di was well known for her signature white polka dot prints.

Stepping away from this Topshop dress for a second, I've also seen another wave of nostalgia for polka dot coming from a widely different source - Pretty Woman. When Vivian stepped out in a brown polka dot cocktail dress, we all secretly wished we had her wardrobe (and access to a bottomless bank account, though sans problematic human Richard Gere). Well, brands like Mango, River Island and Nasty Gal have been riding that wave and people seem to be here for it. Especially on Instagram. All the Pretty Woman references.

3) Someone big wore it.

This is probably the kicker. I know people are weird about influencers, and influencer marketing, and influencer business, and anything to do with influencers. But holy crap, I don't think most people understand just how powerful they are and what wearing a certain item of clothing can do for a brand. I talked to somebody from LikeToKnow.It, that big fashion influencer affiliate programme and they said driven over USD$1 billion in sales through their partners. CRAZY.

In the case of this dress, you had celebs and bloggers wearing it. And more precisely, The Only Way Is Essex's Chloe Lewis wearing it. I don't know what it is about British reality television, but for some reason the viewers really go nuts over things that its stars wear - for instance, Love Island and its retail partner Missguided are just raking in the cash right now. Kate Wright also was snapped wearing it, alongside bloggers like slipintostyle and love_ciandra, and that spurred people to buy it.

Now I've finished my It's Always Sunny conspiracy theory rant, I'm gonna tell you straight up that there is nothing wrong with following a trend or buying something that everybody else has. I know some people get really snippy or condescending about it, but if something makes you happy - get it.

I mean sad ending to this whole Topshop polka dot dress saga: I was hurting for freelance work last month and ended up having to return the dress because I was tight on cash. I literally couldn't justify the £49. When I gave it back and the lady asked me why, I told her it was because I couldn't afford it.

She looked at me, nodded her head and said, 'I feel you.'

And now that god damn dress is going for £200.

I SHOULD HAVE HUNG ONTO IT. IT WAS MY BIRKIN BAG FASHION INVESTMENT MOMENT.

Anyways, if like me you missed the boat or let the figurative boat slip through your fingers, here's some other polka dot dresses that channel a similar spirit.

Fingers crossed they go for loads on eBay...