The pair turned up at the Westfield retail center in London's Shepherd's Bush and surprised passers-by as they set up a stage near an escalator in the middle of the mall.
Shoppers quickly realized the entertainers were in fact the superstar boyband members, and gathered around to watch them perform an acoustic version of the group's biggest hits, including "What Makes You Beautiful."
Horan strummed on a guitar while Payne serenaded the cheering crowds. The pair was followed by a camera crew, sparking speculation the stunt was planned for an upcoming TV show.
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