The former Beatle, 78, was due to embark on a series of European concerts in 2020 including a landmark Saturday night performance on the legendary Somerset festival's Pyramid Stage.

Instead, he spent lockdown on his farm in East Sussex, England, with his daughter Mary and four grandchildren, recording his solo album, McCartney III.

"We were looking forward to touring around Europe and then finishing in Glastonbury, big festival, 50th anniversary," he said.

"So then suddenly COVID struck and nobody could do anything, so the tour was cancelled and Glastonbury was cancelled.

"The only thing that was good about it was it meant I had a lot of time to do other things so I got into the studio and there were some songs I had meant to record, some songs that I was meant to finish up.

"So I did that and I found out I was really enjoying it, it was a good substitute for kind of the disappointment of the tour.

"I ended it up doing it and it ended up as an album. It's surprised me."

McCartney III, which is on course to top the UK albums chart, follows on from 1970's McCartney and 1980's McCartney II.

The veteran musician said the record "snuck up" on him and that he had not been intending to record a follow-up.

"Well I hadn't thought about making McCartney III, no," he said.

"These things are just kind of a care and you don't always think about them, you don't plan them.

"I didn't plan McCartney I or II and so this was the same, this was me just making a bunch of recordings really for my own enjoyment.

"So it wasn't supposed to be an album but then as I played it to people, I played it to my family and stuff I suddenly thought well it is an album, so it snuck up on me."

Australian Associated Press