Taylor Swift wouldn't let her dancers hear her unreleased music.

The 'Shake It Off' hitmaker was so desperate to keep the music from her new album 'Reputation' under wraps ahead of its release that the dancers on the set of the music video for 'End Game' just moved along to a click track rather than to the actual music.

Speaking behind the scenes during filming for her music video, Taylor said: ''I commend them fully because they've been pretending like there's music playing when there's not. I have these [headphones] in my ears. They've been dancing to a click track. It's incredibly hard work.

It is no surprise that Taylor went to extraordinary lengths to keep her music secret as her friend Ed Sheeran previously revealed Taylor's unreleased music travels under lock and key.

He shared: ''She would never send new songs, no. I hear them but has to be with her. I remember when I did a song with her for her album, I was in San Francisco and they sent someone with a locked briefcase with an iPad and one song on it and they flew San Francisco and played the song I've done with her and asked if I like it and I was like 'yeah' and they took it back, that's how I hear it.''

Meanwhile, Taylor's collaborator Jack Antonoff previously revealed the pop superstar always puts her ''heart and soul'' into her music.

He said: ''The sessions were just her and I. She would come over to my apartment, and we would talk and eat and talk more, and the things we talked about turned into songs. She is great at remembering the heart and soul of the process ... But she's really great at knowing what it's about: talking about what the hell is going on in your life and somehow finding a way to take that exact emotion and make a song out of it. That was the theme of those sessions, 'Let's just tell this story, whatever that story is, because that's the whole point.'''