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Daring Duchess!

On Monday, Kate Middleton donned one of her sexiest looks in months at the "Night of Heroes" military awards event at London's Imperial War Museum.

With a dashing, tuxedo-clad Prince William escorting her, the Duchess of Cambridge stunned in a black, strapless velvet gown by Alexander McQueen -- the label behind her iconic wedding gown (and a second reception gown, too).

For the gala -- honoring military servicemen and women -- Kate, 29, also donned private jewelry that she received as wedding gifts. She wore her hair down in her trademark loose, glossy waves. (Despite plenty of pregnancy speculation, the beaming future Queen looked slim as ever for her big night out.)

Kate's brother-in-law Prince Harry was also on the hand for the event, where he and William, 29, presented awards.

In just a few short days, the trio -- plus the entire royal family -- will be ensconced at Sandringham manor, Queen Elizabeth's sprawling retreat in Norfolk, England.

"It will be a difficult baptism in protocol laced with pitfalls," royal watcher Robert Jobson told Us Weekly of Kate's first Christmas with the royals -- and without her own family.

Tell Us: What do you think of Kate's Monday night look!