This is why Kate Middleton always wears white at christenings

The Duchess of Cambridge chose to wear an Alexander McQueen outfit for the christening of Prince Louis today at the Chapel Royal at St James' Palace in London.

It's a nice nod to the christenings of Prince George in 2013, and Princess Charlotte in 2015, as she also opted for Sarah Burton designs then, in a similar shade of cream.

This time round, the dress featured a simple v neck and slightly padded shoulders, and was nipped in at the waist, with a flared skirt.

She accessorised with a 1940s style hat by Jane Taylor and pearl cluster earrings in the shape of a flower.

While there's no Royal etiquette rule that says what the mother of the baby can and can't wear to Christenings, Kate has carried on this little tradition herself.

First off, wearing cream matches the Royal Christening Robe, which is a replica of the fine Honiton lace gown made in 1841 for the christening of Queen Victoria's eldest daughter, Victoria, Princess Royal.

The original gown was subsequently worn for all Royal christenings, including The Queen, her children and her grandchildren, until the youngest of The Queen's eight grandchildren, James, Viscount Severn.

Secondly, there is the connotation of the colour, which often represents purity, innocence and new beginnings - very apt for a christening.

But there might be another significant detail in Kate's outfit this time round: the fact that she wore floral pearl earrings. You see Princess Diana's favourite flower was a white rose, and while the shape is more that of a daisy than a rose, it could be a subtle nod to the late Royal, who never got the chance to meet her grandchildren.