During a conversation being recorded for BBC Radio 4's Mastertapes (in front of an audience with Simon Pegg, Brad Pitt, Martin Freeman, Paul Weller, and Noel Gallagher), Sir Paul McCartney talked to John Wilson about dealing with depression after the Beatles break-up in 1970. "It was very depressing. You were breaking from your life-long friends. We used to liken it to the army—we had been army buddies for a few years, and now you weren't going to see them again."
The depression led to drinking, which isn't really the best cure for that. So when McCartney's wife, Linda, told him "You gotta get it together, we gotta do something," they formed the band Wings. He explained:
People said to me, 'Get a big supergroup with loads of stars,' but for some mad reason I wanted to go back to square one and do it as we did in The Beatles. So people said, 'Well, Linda can't play keyboards', and it was true. But you know, we couldn't play guitar when we started. . . We knew Linda couldn't play, we knew we didn't know each other, but she learned. We had some funny experiences. Looking back on it, I'm really glad we did it.
In the interview, when the subject of Wings' general reception with critics arose, McCartney also conceded, according to The Telegraph, "We weren't very good" and "We were terrible." [Author's note: After several viewings, I don't hear the part where he says "We were terrible" but BBC and other outlets say it's there, so… maybe it happens in a part of the interview that wasn't filmed or included in the BBC clip. This post will be updated with any further information.]