The Duke and Duchess of Cambridge, who are both fans of the British singer, specifically chose her to perform a rendition of Elton John’s “Your Song” (one of Diana’s favourites) for their first dance as man and wife.
Ellie admits it was difficult to keep quiet about her secret performance.
“I kept it to myself for so long – but no one would have believed me anyway,” she told Maire Claire UK.
The 27-year-old pop-synth star went on to praise the royal pair, saying Kate and William spoke to her “quite a bit” throughout the night.
"They're just a really awesome couple, lovely people, so I understand why people are fascinated bythem," she said.
"It was a really beautiful night – but then, I haven't been to many weddings."
When asked if she, too, would like be married someday, the songstress replied: “Well, it might be nice to have a wedding one day, mightn’t it?," adding, “I quite like being by myself. What’s wrong with that?”