Shawn Mendes brought out Niall Horan at his show in London for a surprise duet of "This Town." "I'll remember this for a long ...

Shawn Mendes invited former One Direction singer Niall Horan to join him for a surprise duet of Horan's debut solo single ...

Shawn Mendes and Niall Horan perform 'This Town' in London during concert performance, following last year's 'Treat You Better' duet.