The Duchess of Cambridge dazzled in a dress by Alexander McQueen and a hat by Jane Taylor as she arrived at St Paul's Cathedral.
She chose the nude-coloured, knee-length lace dress with long sleeves for the service of thanksgiving in celebration of the Queen's Diamond Jubilee.
It is not the first time she has worn the designer for a high profile event - her wedding dress was designed by Sarah Burton for Alexander McQueen.
She also wore a bright red Alexander McQueen dress for the Diamond Jubilee River Pageant on Sunday.
Princess Beatrice wore a Kinder Blue coat dress with tan-coloured Gina stilettos.
Her hat was by Stephen Jones while her bag was designed by Lemeresca.
Princess Eugenie wore a purple dress by Suzannah. Her bag was by Loro Piano and her mushroom-coloured nude stilettos were also by Gina.
Her hat was by the same designer as her sister's - Stephen Jones.