The two guys were taking a break from recording the new One Direction album, so they stopped by the London Westfield mall to give fans a surprise show.
The concert is part of their new documentary that they're making, so there were also some cameras on the scene to capture Niall and Liam's performance. Their London fans are definitely happy with the guys' little surprise.
Here's a video that a fan took of the mini-concert:
Vídeo: Olivia Connelly