The singer was personally invited to play at the party by Prince William and Kate Middleton, who are said to be big fans of her music.
Speaking of the event, Goulding told the News of the World: "It was an amazing honour to be asked to perform by Kate and William. It's a night I will never forget."
Goulding performed covers such as The Killers' 'Mr Brightside' and Stevie Wonder's 'Superstition', as well as a selection of her own songs - including Lights, The Writer and her cover of Elton John's 'Your Song'.
A source said: "It was a clear yet subtle nod to Princess Diana because she loved that song and William knew that. Elton is also very important to William because of his role at Diana's funeral.
"Ellie's performance was spectacular and even Prince Charles and Camilla ended up slow-dancing on the floor before they bailed out and left it to the young ones.
"Kate wanted to make sure there were songs everyone would get up and dance to. She and Wills are huge fans of Ellie so they were most excited by her original songs and danced to most of them. Kate sung along to every word of her last song 'Starry Eyed'."
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