One Direction star Niall Horan has expressed his delight after the band performed at the London 2012 Olympic Games Closing Ceremony.

The former X Factor contestants were one of many acts who played the massive event in London last night (August 12), with the likes of Jessie J, Spice Girls and George Michael also taking to the stage.

One Direction played their hit track 'What Makes You Beautiful' at the Olympic Stadium shindig and Irishman Niall Horan took to Twitter soon after to call the Olympic cameo the "highlight" of their career. He said:

"Omg that was unbelievable,highlight of out career, and the biggest audience we will ever play to 1 billion people! #ThankYouLondon2012."

Horan continued: "Met soo many incredible people today! The who, brian may, spice girls, take that! liam gallagher, just a day none of us will ever forget. Words can't describe how it felt tonight! Best feeling ever! #london2012ClosingCeremony."