The 49-year-old singer has kept fans entertained during the coronavirus lockdown by teaming up with the likes of Niall Horan and Sir Cliff Richard on YouTube - and he's now poised to perform with the Coldplay frontman.
A source told The Sun newspaper's Bizarre column: ''What started out as a bit of fun has picked up speed and now he's got everyone who is anyone agreeing to take part.''
Gary has been thrilled by the response to his 'Crooner Sessions'.
He shared: ''These sessions have shown me what brilliant friends I have, who I can message saying, 'You wanna do this?' and the next minute, it's changing people's days.
''All these years I've been in music, this is the result - not the songs or tours. It's seeing people you've known for years, or months, supporting one another and making people feel great.''
Gary is also currently working towards completing his first solo orchestral album, which he hopes to release later this year.
And the singer feels fortunate that he managed to complete a significant amount of the album before the lockdown was introduced.
He told Variety: ''Thank goodness we got our 60-piece orchestra into one room before lockdown!
''It's a great change for me. Making an album with an orchestra makes you write and sing differently. There are no laptops - just humans playing music together.
''Sixty people can make the most incredible sound, that brings you to tears. It's an example of the great things we do as big groups, so it feels very of-the-moment.''
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