Ed Sheeran struggled to get in touch with Beyonce over their new duet because she constantly changes her email address.

The British singer and the American superstar released their version of Perfect on Thursday (30Nov17), with the tune originally appearing on his third studio album รท (divide).

Ed and Beyonce started work on the duet several months ago, and he was particularly amazed by her professionalism during the project, as she had just given birth to twins Sir and Rumi.

"I have an email address I email (to get in touch with Beyonce)," Ed told Entertainment Tonight backstage at KIIS-FM's iHeartRadio Jingle Ball on Friday (01Dec17), adding that Beyonce's email address "actually changes every week".

"So, I emailed that and we got on the phone, and it's been in the works since May. Obviously, she had twins (in June), and we finished (the song) in September, so I've been holding onto it since then."

As well as appearing on the track, Ed explained that Beyonce had suggested they keep the sound simple by just having acoustic guitar playing in the background. And the star divulged that the Formation hitmaker nailed her part in just one take.

"When we got in together, it wasn't so much notes, it was very much like a back and forth thing, like, 'What'd you think of this?' Or 'What do you think of this?' and (we were) probably in the studio for four hours," the 26-year-old shared. "She (Beyonce) was just like, 'Right!' Went in, one take, came out, like, 'Yeah, that sounds alright!'"

During the interview, Ed also quashed rumours that he would be performing at Prince Harry's wedding following his engagement to Suits actress Meghan Markle.

"I get asked this all the time like I know the Royal family. I've met Harry once!" Ed joked. "(And) that was in 2011 at his gran's Jubilee, and it was like, 'Hey.' 'Hey'... I barely know him!"