Kate Middleton's latest accessory is a bit of a huge deal for the Queen

(Image credit: Rex)

Last night Kate Middleton attended a state banquet for the official visit of the King and Queen of the Netherlands in London, and naturally dressed for the occasion.

She wore a pale blue ballgown by Alexander McQueen, as well as one of Princess Diana's favourite pieces of jewellery, the Cambridge Lover's Knot tiara, a pearl and diamond affair given to her on her wedding day by the Queen.

The Duchess has actually worn it at several events, so it appears to be one of her favourites too.

But it wasn't the diamonds that everyone noticed, it was the accessory she pinned to her breast. You see the seemingly innocuous brooch is actually a sign that she has been given the Royal Family Order.

The Queen presents it to female members of the Royal Family (only 15 so far) and they're only worn at white-tie events.

The brooch is bordered by diamonds and surmounted by a Tudor Crown in diamonds and red enamel, whilst the reverse, in silver-gilt, is patterned with rays and depicts the royal cypher and St Edward’s Crown in gold and enamel.

Kate's is a little different though, as it's painted on glass rather than ivory like the others, a not to Prince William's ivory ban.

However the Duchess did not wear a blue sash like Camilla or the Queen, as she is not yet a member of the Royal Victorian Order yet, which is likely to come when she has a few more official engagements under her belt.

Penny Goldstone

Penny Goldstone is the Digital Fashion Editor at Marie Claire, covering everything from catwalk trends to royal fashion and the latest high street and Instagram must-haves.

Penny grew up in France and studied languages and law at the Sorbonne Nouvelle University in Paris before moving to the UK for her MA in multimedia journalism at Bournemouth University. She moved to the UK permanently and has never looked back (though she does go back regularly to stock up on cheese and wine).

Although she's always loved fashion - she used to create scrapbooks of her favourite trends and looks, including Sienna Miller and Kate Moss' boho phase - her first job was at MoneySavingExpert.com, sourcing the best deals for everything from restaurants to designer sales.

However she quit after two years to follow her true passion, fashion journalism, and after many years of internships and freelance stints at magazines including Red, Cosmopolitan, Stylist and Good Housekeeping, landed her dream job as the Digital Fashion Editor at Marie Claire UK.

Her favourite part of the job is discovering new brands and meeting designers, and travelling the world to attend events and fashion shows. Seeing her first Chanel runway IRL at Paris Fashion Week was a true pinch-me moment.