According the U.K. newspaper The Daily Express, McCartney recorded without an instrument to accompany his vocals. He told Culture magazine: “Here was I in this completely new role, feeling really quite intimidated. There was nothing to hide behind, no guitar or piano that I could put between me and ‘it.’ I had to sort of find a vocal style...
“I’m in front of really good musicians, who know what’s going on, and I’m thinking, ‘Bloody hell, I’m going to totally disgrace myself here. I’m going to be, like, the worst person in this band, and I’m supposed to be, like, not bad. They’re all going to be smiling at me, but secretly thinking, Jesus Christ, this guy is rubbish.’ Then I think, ‘Get it together, Macca, come on.’ ... So, yeah, me not having an instrument was very strange, very intimidating.”
The former Beatle’s new album is due out February 7. In addition to Krall, Eric Clapton and Stevie Wonder appear on Kisses on the Bottom.