The millions who have seen clips of Billie Eilish scoop five Grammy Awards probably assumed the smartly-dressed man leaping to his feet in delight right behind her was some sort of music industry bigwig.

He is not. Terry George, from Leeds, is a successful businessman, but he says he found himself among the US pop prodigy's entourage after winning the chance to be a seat-filler at the star-studded ceremony in Los Angeles.

Until recently, the 54-year-old admits, he thought Billie Eilish was an Irish comedian.

But on Sunday, he found himself chatting to the 18-year-old superstar while in the middle of the celebrations when she and her brother - who is her producer - won.

"I felt part of the entourage," George tells BBC News. "I don't know if she was just overwhelmed with the whole emotion of it all, but she and her brother grabbed my hand and shook it when they came back down [from the stage].

"Just being there, hearing the gasps and hugging people around them like their mum, I just felt quite caught up in it all.

"It was was pretty incredible really."

Image copyright Getty Images Image caption Terry George (right) behind Jay-Z and Beyonce at the 2017 Grammys

This was the fourth year that George has been a Grammys seat-filler - he has previously rubbed shoulders with Beyonce, Madonna and Rihanna.

Ceremonies like the Grammys use members of the public to fill seats to make it look like there are no empty spaces when stars go backstage or to the bathroom, or don't turn up at all.

Image copyright Getty Images Image caption Just a casual chat with Madonna, Nas and Lang Lang at the 2015 Grammys

"I heard that Taylor Swift was going to be sitting where I was," George says. "I don't know how true that was."

(Swift was nominated for three awards but didn't attend, with sources telling Variety she dropped out of performing several days before.)

The role of the seat-filler has received more attention this year after Lewis Capaldi - who lost out to Eilish for song of the year - said a woman mistook him for one, possibly as a result of his laid-back (i.e. scruffy) appearance.

George made the same mistake. "To be honest, I didn't even know what he looks like," he says. "I thought he was a seat-filler as well. He looked very casual."

He explains: "They move you around all the time, but I tended not to move around so much on this occasion.

"I was one seat away from the stage - three footsteps and I would have been at the bottom of the stage steps. It was that close."

The ceremony cameras showed him cheering enthusiastically directly behind Eilish as she looked ever more stunned each time she completed one part of her clean sweep of the show's main awards.

"They were all very chatty and talking and I could just feel the atmosphere, and [hear] the gasps when she was getting called out," he says.

Image copyright Getty Images Image caption "Where have I seen that guy before?" Rihanna and Katy Perry at the 2015 Grammys

George was close enough to listen in to Eilish and brother Finneas O'Connell as they tried to comprehend what was going on.

"She'd done a speech and they came down and they were saying, 'How do you think the speech went? I didn't know what to say.'

"I think they were pretty surprised that they were winning the awards."

And he was close enough to have a conversation with the singer herself amid the whirlwind.

"She looked round to me and caught my eye, and I said, 'What are you going to do if you win this next one?'" he recalls.

"She was clenching her hands really tight and really gasping, and she said, 'Oh, my goodness, I don't know what I'm going to do, I don't know what I'm going to do.' You could hear the anticipation in her voice."

'Are you her grandad?'

Other people in the audience on Sunday also assumed that George, in his tuxedo and open-neck white shirt, was part of Eilish's inner circle.

"People kept saying to me, 'Are you her grandad?'" he laughs.

"I thought, I'm not that old. Maybe I am actually! I just smiled. I thought it was kind of funny."

George's businesses include a portfolio of bars, clubs and hotels in Leeds. He has appeared on TV in the UK as the benefactor on The Secret Millionaire, and on I Own Britain's Best Home on Channel 5.

But he says his presence at the Grammys was not down to his business connections or deep pockets. "It's not something that's paid for," he says. He and a friend enter a ballot to be seat-fillers, and he has been successful four times in the past seven years, he says.

"I feel kind of blessed to have even got to be at the Grammys, but to have witnessed such a historic occasion and being placed next to Billie Eilish was like winning the golden ticket," he says.

Follow us on Facebook, or on Twitter @BBCNewsEnts. If you have a story suggestion email entertainment.news@bbc.co.uk.