In reply to j.

It was not mimed, and Graham Norton performances are always live. The echo of his voice was just an audio effect that they added, but it was all live. You can tell when Bruno sings "Can I just stay here, spend the rest of my days here", his vocals are a bit shaky (still a good performance overall though), and he also changes the way he sings the beginning of the second verse. Some of Bruno's band members shade so many artists who use playback lol. Even in the actual 'Locked out of heaven' music video, Bruno and his band were actually performing the song in front of the crowd of girls- not lip syncing to it like most artists do in videos.