The One Direction hunk - who has previously worked with Burning Beaches' singer Sam McCarthy - has been penning songs with the indie musician for the band's new album, but Gary is unsure whether the tracks will make the cut.
Speaking to The Sun newspaper, Gary said: ''We wrote with Harry. It was a lot of fun. He's a real dude actually. We've no idea if those songs will make it yet, though.
''It's a long process. It's great to work with other people -- it's good to flex the muscle.''
Meanwhile, the heartthrob is also said to be collaborating with Take That star Gary Barlow after the pair met in New York City.
A source said previously: ''Gary has been over in New York working on music for a Broadway musical version of 'Finding Neverland'. He heard Harry was in town and arranged to meet up.
''They had a great afternoon talking about Gary's life in Take That as a young bloke and then more recently. Harry is an attentive guy and really listens. He likes keeping older company and soaks up as much advice as he can get.
''Gary talked him through his songwriting techniques and offered to write with him whenever they get the chance.''
However, One Direction - also consisting of Zayn Malik, Louis Tomlinson, Liam Payne and Niall Horan - show no signs of parting ways to explore solo careers after recently signing up to a three-year contract, which mean they will lose out on millions of pounds if one of the band members was to walk away before the contract time is completed.
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