Kate Middleton and the Queen are never seen wearing this one beauty product

Apparently it's against the 'official' dress code

You might already be familiar with the fast-selling fashion and beauty staples Kate Middleton swears by. There's the set of (mostly) British designers she regularly calls on for one-off appearances or tour wardrobes, the classic square clutch bag she's rarely seen without and the catwalk beauty trends she channels in real life.

We also know the Queen is also no slouch in the style department, whether she's throwing shade with her 'Brexit' hat or giving us vintage fashion inspiration with her style file.

But there's one thing you're very unlikely to ever see the Queen or Kate Middleton ever sporting - other than leather chaps, embellished Crocs or a Sex Pistols teeshirt - and that's colourful nail varnish.

According to OK! Magazine, royal sartorial rules dictate that only natural-looking nails can be worn to official events. The Queen herself has been wearing the same £7.99 shade of nail polish since 1989, a polish Kate also wore on her wedding day in 2011.

The Duchess has continued the trend for neutral nails since marrying into the Royal family. But though she generally wears a closed-toe shoe, she has been known to flash a bit of red pedi when she goes for a strappy sandal (wild).

Interestingly, during her first official appearance with Prince Harry at the Invictus Games last month, Meghan Markle paired her ripped jeans and teeshirt look with a natural manicure, so perhaps she's also been picking up some royal dress code tips.

There's probably a WhatsApp group...