Liam Payne writes sweet tribute to One Direction bandmate Louis ...

Liam Payne has written a touching post about his former One Direction bandmate Louis Tomlinson, as the latter premiered his documentary All of Those Voices.

The film promises to give "an intimate and unvarnished view" of the singer, showing fans the ups and downs of both his career and personal life, and will be screened for a limited time in cinemas from next week.

Following the premiere in London's Leicester Square this week, Liam took to his Instagram to apologise to Louis for not being there for him enough in the 1D days.

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"I'm so sorry I was so out of my mind and I didn’t do better for you, I feel ashamed in those moments to not be as good of a friend as you have been to me," he wrote. "At least I have time now and I’m me again so will try and make amends.

"I'm emotionally drained watching the movie and I only did an hour and a half, you lived it and I’m so proud of how you did it not only with amazing music but with passion and the will to get up off the canvas every time life beat you down and fight back.

"I'm so thankful to have you in my life mate[.] I feel so lucky and I know you know this but you were part of a small group of people that literally saved my life, you dragged me out of something so dark I've never shared it but your approach is something I admire and aspire to so I can one day do the same.

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"Thank you Louis and congratulations you deserve all these moments, every sight you get to see, every cheer that you hear and all the love you are receiving from the world.You worked harder than any of us to get here and now the world gets to see that from your side…"