Cressida Bonas attends the Art Antiques London Gala Evening in aid of Children In Crisis at Kensington Gardens on June 10, 2014 in London, England. Credit: David M. Benett/Getty Images

See that, Prince Harry? The royal's ex-girlfriend Cressida Bonas stepped it up a notch at the Art Antiques London Gala Evening on June 10.

With her blonde hair down, the 25-year-old sizzled in a silver and black backless jumpsuit, which showed off some serious sideboob.

Bonas "looked confident and was in a great mood," an onlooker tells Us Weekly, adding she spent much of the evening chatting with good friend and host of the fete Princess Eugenie, who is Prince Harry's cousin.

Since splitting with Harry in April after two years of dating, Bonas has bounced back beautifully. Cressie hit the town with Princesses Beatrice and Eugenie last month, looking stunning in a long navy halter dress, partying until the early morning hours.

The blonde has also landed her first movie role. A source confirms to Us Bonas is set to star in Harvey Weinstein's Tulip Fever alongside Victoria's Secret model Cara Delevingne and Daisy Lowe.