Speaking to Kate Thornton on White Wine Question Time, the musician and TV personality spoke about his early gig playing in working men's clubs and bingo halls, and how he would travel to London for a day to sit in label reception areas, before visiting music shops in Soho.
He said he used to travel down on the train with a packed lunch made by his mum.
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He told Thornton: "I often used to sit in reception at 20 Manchester Square, EMI, and wait for people to come past and some days no one would come past.
"I used to have a little envelope with songs in. Now and again someone would come out and I'd go: 'Can I [give you my music]?' They'd say: 'Oh, don't give it to me. I'm just an accountant here.'
"Now and again an A&R person would come out and you'd give them a cassette and the phone number on it."
He told Thornton that he never got a single call from doing it. He'd get a McDonald's at Tottenham Court Road and then head back home on the train again. He said all his money earned at that time went into recording equipment.
He added: "I was working at that time, so money wasn't an issue for me. I was working possibly every night of the week, maybe not a Monday or Tuesday. But I never had any money because whenever I'd earned money, I'd buy a piece of equipment, I was building a studio.
"So by the time I gave my demos to Nigel Martin Smith, who's the manager of Take That it was like 20% off a finished record."
Barlow, who turned 50 this year, also admitted to Thornton that he would have loved to have written Oasis's hit Wonderwall, calling it "a brilliant song".
He said some songs such as Billie Jean and Wonderwall didn't need to be grouped by their genre, but that sometimes people got caught up in wanting to define them.
He added: "You don't even need to define these songs. Billie Jean doesn't have a genre.
"I don't think Wonderwall does. There's so many songs that just don't have genres because they're just great songs."
Gary's new album The Dream of Christmas is out now. Tickets for the 'All The Hits Live' tour are available from garybarlow.com/tour and Gary Barlow Organic wines are available exclusively in Morrisons or at garybarlowwines.com.
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