The actress, 33, who dated Prince Harry for three years until 2014, opted for a £42 Mary Katrantzou x Lipsy Tiered Skirt Midi Dress for the party in central London.
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Cressida Bonas, 31, has shared first selfie with husband since their July wedding
Prince Harry s ex tied the knot with Harry Wentworth-Stanley last summer
Posted snap online as she snuggled up with Harry during a walk through snow
Comes after she revealed she planned 30-person nuptials in under two weess
Donned an old Whistles dress that she once wore for a James Arthur music video