The Princess of Wales marked a royal first this week, visiting the 1st The Queen's Dragoon Guards for the first time as Colonel-in-Chief of the regiment.
Stepping out in Norfolk, Princess Kate, 41, surprised in an all-black outfit consisting of sleek trousers, fitted turtle-neck knitwear and a silhouette-skimming blazer.
Her monochrome dressing was a rare sartorial move for the royal, considering entirely black outfits are usually reserved for periods of mourning.
With nothing but a symbolic red poppy brooch pinned to her lapel adding a pop of colour, the Princess's unusual single-toned ensemble was a rare change from her usual rainbow dressing.
© GettyAccording to Matthew Storey, curator at Historic Royal Palaces, "mourning dress has been part of European royal culture for centuries, but it reached its peak in the 19th century with the influence of Queen Victoria."
He told the Telegraph: "Widows were required to wear black, then either white or mauve, for at least three years before being able to return to richly coloured clothing."
© GettyIt's incredibly rare to see a member of the royal family wearing an entirely monochrome outfit during an official daytime engagement. While it's not strictly enforced, royal etiquette dictates that black is reserved for mourning periods only.
© WPA PoolAdding to her sober and sophisticated aesthetic, the Princess of Wales wore her new glossy bangs swept into a side parting, reverting to her go-to hairstyle of the early 2010s.
SEE MORE: 10 poignant photos of the royals in mourning dress - touching tradition revealed
In a recent conversation with HELLO!, celebrity hairstylist Chris Appleton revisited the Princess' best hair moments through the years - and revealed the modern change he'd make to her famous wedding hair.
© GettyKate's trailblazing 'Demi Chignon' wedding hair broke a 350-year royal tradition of bridal updos, with cascading curls falling behind her tulle veil.
"If Kate was getting married today, I'd modernise that look with a centre parting. She has such a beautiful face I would've framed it with a softer, tailored look, maybe even with the curtain bangs down. The curls looked quite set too, I'd brush them out to give them a bit more fluidity," he said.
LISTEN: Find out what Prince William's name will be when he becomes King
