Prince George and Prince William at Princess Charlotte's christening

We don't think we'll ever be able to forget how just cute Prince George looked at his sister's christening on Sunday.

Our hearts melted the moment we caught sight of the toddler walking along wearing a printed red and white smock set.

His side-parted blond hairstyle and T-bar shoes only added to the adorableness of Kate Middleton and Prince William's first child. 

Prince George's retro outfit was crafted by Rachel Riley, a designer known for creating miniature ensembles with a throwback feel. 

Proving he follows in his mum’s footsteps when it comes to predicting the next big thing in fashion, the £85 summery embroidered two-piece started flying off the shelves.

The shirt and matching shorts quickly sold out in sizes 18 months and 2 years moments after he was snapped rocking them at the Sandringham Estate. But for anyone keen to buy it, it's just been restocked.  

‘It has been very popular in the last 24 hours,’ Rachel Riley confirmed earlier this week.

‘Of course we get a spike on the website – he’s a high profile baby.’

It's not the first time 'The George Effect' has been apparent. The sales of Crocs shoes soared after the almost 2-year-old stepped out in some. 

Rachel - who described the rest of the royal clan as looking 'lovely' - reckons that parents can educate their kids by dressing them in a particular way. 

Could this be the reason Kate, 33, and Wills, 33, decided to pick such a sophisticated get-up for gorgeous George?

'If you dress children smartly, you help them to understand you don’t have to lie on the floor and run around, and disrupt other people’s whatever,' she continued.

'It’s part of their education - if they are dressed for a special occasion they will be aware of that and their manners might reflect how they were dressed.'

For more on Prince George, check out our round-up of Princess Charlotte's big day

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Royal family at Princess Charlotte's christening