Kate swaps glittering tiara for a casual ball cap

Only the Duchess of Cambridge can go from wearing a dazzling diamond tiara to a basic ball cap in the space of 24 hours!  Last night, Kate and William attended their first white-tie event, the annual Diplomatic Reception hosted by The Queen at Buckingham Palace. Here they are arriving at the Reception in a chauffeur-driven Bentley.

For the first time since her wedding day, Kate donned a tiara.  The Queen loaned the Duchess the Papyrus tiara, also known as the Lotus Flower Tiara, which once belonged to the Queen Mother.

She paired the tiara with The Queen's diamond chandelier earrings, which she has previously worn to the Los Angeles BAFTA reception in 2011.  Kate's dress is believed to be a bespoke Alexander McQueen lace gown.  This was a private function so unfortunately we don't expect any photos will be released of the event.

Today, PopSugar posted exclusive photos of the Duchess casually strolling through Kensington Gardens with baby Prince George and donning a baseball cap. These are the first paparazzi shots taken of Kate with Prince George, and it remains to be seen how the Palace will react to this privacy breach.

Kate layered up with her waxed Barbour 'Defence' jacket, sweater and scarf. The sweater is speculated to be by Zara.  The Barbour 'Defence' jacket has been discontinued, but here is a lovely repliKate from Calvin Klein.

Barbour Ladies' Wax Defence Jacket - Olive (SOLD OUT)

RepliKate: Calvin Klein US$129

Kate also appears to have worn her much-loved J Brand 811 skinny jeans.  They've been a staple in Kate's closet over the past couple of years and we've seen her wear them on many occasions.

J Brand '811' Mid Rise Skinny Jeans (Navy) US$169

Kate kept her hands warm and toasty with Fownes gloves which she first wore during a 2011 visit to St. Andrews University.

The hat appears to be her Tactical 511 cap, seen previously in 2008 at a polo match with Prince William.