Lily Allen says her kids were baffled by how famous she was after watching her perform at Glastonbury

When Lily Allen walked out on the Other Stage during Olivia Rodrigo's Glastonbury set last year to sing her hit single 'F**k You', fans were absolutely floored.

But, apparently, no one was as surprised as Allen's two daughters, Ethel and Marnie, who had no idea their mum was such a popular singer.

Speaking about the groundbreaking Glasto moment on The Jonathan Ross Show, Allen revealed that she agreed to do it because her daughters were such huge fans of the 'Drivers License' singer.

"Ethel, who is my oldest, was sitting next to me at home one evening, when I got an email from somebody that I sort of used to know [that] said, 'I'm working with Olivia Rodrigo. Would you like to perform with her at Glastonbury?'" she explained.

"And Ethel was looking over my shoulder. She was like, 'If you don't do that, I will never talk to you ever again'.

"So, I said, 'Yeah of course, I'd love to do that'."

The singer has previously admitted that, before walking out on stage with Rodrigo, she didn't know if she'd be able to perform sober, due to her past battles with addiction.

But, knowing how much it would mean to her kids, Allen decided to go ahead with it anyway, and it was a huge hit - much to her daughters' surprise.

"I don't know what they were expecting, I kind of think they thought maybe I was going to be singing, like, back up or something," Allen laughed.

"I was really, really nervous because I haven't done it for a long time, I haven't done it sober... I kind of was slightly expecting her to introduce me and people be like, 'What? Who?'

"But it wasn't like that. It was really, really amazing. People went absolutely ballistic. And so I was really overwhelmed.

"But my kids were just like, 'What is going on?' Because, you know, Olivia Rodrigo is like their idol and they couldn't really get their heads around the fact that people are kind of screaming even louder for me than they were for her at some points.

"So they were just very, very confused."

After the stellar performance, which took aim at the US Supreme Court who had recently overturned the Roe v Wade law, Allen's kids were a little lost for words.

"Then we kind of got offstage and they were just - they didn't really want to talk to me," Allen recalled.

"They were a bit sort of overwhelmed by the whole thing.

"And then we got in the car, on the way back, and Marnie looked at me and she went, 'So... were you kind of popular then?'

"I was like, 'Yeah!', and she was like, 'What, like, in the charts?' and I was like, '...Yes!'"

And that, folks, is how you know you're getting old.