One fan tweeted: “How lovely are Edward and Sophie’s children Lady Louise and James.”
Another person tweeted: “Sophie Wessex loving this.”
Royal watcher @paulaarsans said: “I really like her style now. Very youthful and a bit boho.”
Sophie looked as though she was enjoying the celebrations and was photographed smiling and laughing.
The family joined other members of the Royal Family in the Royal Box to watch the party in honour of The Queen.