Some 300 of the new Duke and Duchess of Cambridge's closest family and friends will celebrate with dancing and dinner at the black tie do, which will stretch into the early hours.
The Queen has given over the home to the wedding celebration as revellers including the couple's close friends Guy Pelly and Thomas Van Straubenzee attend.
Kate, in her gown for the evening, leaves Clarence House alongside Camilla Parker Bowles for the short journey to Buckingham Palace
Kate's second dress is a strapless white satin gazar evening dress with a circle skirt and diamante embroidered detail round the waist. William stuck to the safe bet of a dinner jacket and bow tie
Mrs Middleton wore a black capped sleeve dress, cut low at the front and back, with a tiered skirt while her daughter Pippa opted for a long emerald green sleeveless dress with a jewelled embellishment on the front and a plunging neckline