The 26-year-old princess wrapped up against the cold in a padded jacket, navy dress, tights and black ankle boots, accessorising her look with a shimmering scarf.
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Joining Beatrice at the seasonal Hyde Park event was Chelsy Davy, Prince Harry's ex-girlfriend. Lawyer Chelsey was snapped laughing and joking with her friends and enthusiastically hopping on and off the fairground rides.
The extensive celebrity guest list also included Helena Bonham Carter, Kelly Brook, Tom Daly, Jodie Kidd, Danny O'Donoghue, Suki Waterhouse, Jason Donovan and Matt Smith.
Paul Weller's children Natt, 24, and Leah, 21, from his marriage to singer Dee C. Lee, also entered into the event's festive spirit.
Strictly Come Dancing star Brendan Cole and his wife Zoe took a night off from looking after their one-year-old daughter Aurelia to enjoy Winter Wonderland's delights.
Brendan is currently hoping to take the title of 2014's Strictly champion with his dance partner and Casualty actress, Sunetra Sarker.