Katy Perry has revealed she spent the night in Windsor Castle ahead of delivering a spectacular performance at the King’s Coronation concert.The US singer, 38, gave electric renditions of her hit tracks 'Roar' and 'Firework' at the celebratory event held in the grounds of the castle on Sunday evening, dedicating the latter to the King in honour of the work they do together with the British Asian Trust and their Children’s Protection Fund. Dressed in a glistening, metallic-gold, voluminous ballgown which featured a train and matching sleeves, she made a dramatic entrance by walking out singing the opening lyrics to 'Roar' as a drone projection of a lion’s head graced the sky above her.The upbeat pop song was enjoyed by Princess Charlotte who could be seen singing along with the American pop star, next to her mother the Princess of Wales, who swayed along to the song.The performance was accompanied by a dazzling light display which lit up the audience and the sky.