This is the reason Princess Charlotte never wears trousers

As you know, there are many fashion rules the royals have to follow, from Kate Middleton not wearing wedges in front of the Queen to Meghan Markle not wearing tracksuits in public.

And these rules also apply to the royal children. For instance, Prince George always wears shorts for this reason, and eagle-eyed observers have questioned whether there's a reason Princess Charlotte always wears dresses.

You might have noticed that the 3-year-old also often wears old-fashioned smock dresses with ruffles and a peter pan colour, and this is apparently so that she'll never appear 'out of date'.

Kidswear designer Rachel Riley (a favourite of Prince George's) explained to the The Telegraph: 'If they wear very simple things… it's timeless in that you can't really date a specific photo or put them in something that seems out of date. They have chosen a very traditional look and are a traditional family.'

There are no official rules saying little girls can't wear trousers, however according to royal expert Marlene Koenig, this tradition dates back a long time.

She told BAZAAR.com, 'If you look at photos of young royal girls – from Princess Anne to Charlotte, you will notice that they tend to wear smocked dresses as little girls when they are in public with their parents.'

'If the duchess is in a dress in public and Charlotte is with her, most likely Charlotte, at this age, will be in a dress – also in formal portraits, or on the balcony for the Trooping of the Colour.I expect that when the kids are at home, playing in the nursery or in the backyard, they are wearing more casual clothes,' she added.