Billie Eilish worried she'd wet herself with excitement on hearing her Bond theme tune on the big screen.

Billie Eilish

Billie Eilish

The singer performs the title track, 'No Time To Die', from the James Bond film of the same name - which finally got its premiere on Tuesday night after months of delays - and she admitted she was very excited by the "crazy" turn of events.

She said: "It's going to be crazy. Oh my god, I'm gonna pee myself."

Billie wrote the song with her brother Finneas and they both always wanted it to be a "big moment".

She told the BBC: "We still wanted to have a big moment because it's a Bond song. And as much as I'm known for singing quietly, I guess, I was just like, 'I'm gonna prove I can do this other stuff too.'"

Billie had previously revealed she suffered "an intense amount of writer's block" when she tried to pen the 'No Time To Die' theme song, as she explained that it wasn't a straightforward process.

Billie said: "We had an intense amount of writer's block as soon as we were called to action."

Finneas added: "We rented out a studio to go and try to write it - and we didn't write anything good."

Billie and Finneas eventually ended up penning the song on a tour bus in Texas.

She explained: "Finneas came up with this piano motif and immediately we were like, 'Ohhhhhh', and we wrote the whole song."

Billie and Finneas had both dreamed of creating a Bond theme song long before they were offered the opportunity.

The 'Bad Guy' hitmaker said: "We'd always wanted to write a Bond song - even before it was an option."

And her sibling added: "We'd been writing motifs and thinking of melodies for a couple years, just as far as like, 'Wouldn't it be cool if one day we got to do a Bond song?' And when we got wind that they were making the 25th, we immediately set out to meet with Barbara [Broccoli, producer] and plead our case."