Two members of One Direction wowed shoppers at London's Westfield shopping centre earlier today (August 2) by performing an unannounced live set.

Niall Horan and Liam Payne turned up to the Shepherd's Bush mall this afternoon and treated members of the public to an impromptu gig, in which Horan played the acoustic guitar and Payne took over vocal duties.

Pictures posted to social networking site Twitter by the group's fans show the pair performing next to some escalators while being accompanied by a small backing band dressed in matching black T-shirts emblazoned with the slogan, 'welcome to London'.

Westfield also shared a picture from the exciting surprise mini-concert via Facebook and included a caption that read: "Guess who made a visit to Westfield London this afternoon? Niall Horan and Liam Payne from One Direction, took a day out of their busy schedule to play a surprise gig!"

Payne took to Twitter this morning and told his 5 million followers that One Direction were spending the day in the studio: "Woop wooop studio timeee I think you guys are gunna love it"

Watch One Direction's live rendition of 'More Than This' from the Sirius XM studio below: