Speaking at a recording of BBC Radio 4's Mastertapes at London's Maida Vale studios McCartney spoke about writing with Kanye on "All Day" and "FourFiveSeconds." “I love Kanye and he loves me. He’s a monster," McCartney said. "He’s a crazy guy who comes up with great stuff, so he inspires me. It was definitely different, because we never appeared to write a song. A lot of what we did was just tell each other stories.”
McCartney went on to explain that they would sit together and chat while he strummed melodies on his guitar. He'd leave the studio and Kanye would send him full songs based on his noodling. "All Day," for example, came from McCartney telling Kanye about a guitar chord he saw in a Pablo Picasso painting. “I was telling that to Kanye…and he didn’t really appear to notice. But then after Christmas, I get this track back, and he took my melody and made it seriously urban.”
The episode of Mastertapes will be broadcast on BBC Radio 4 on May 28. Watch a clip above.