If you want to rue the pop music events that did not happen in 2020, you can add to the list the fact that Paul McCartney had planned to sing “Shake It Off” with Taylor Swift when they both would have been headlining the Glastonbury Festival in the UK this past summer.

Not that Swift herself was aware of this. “It would’ve been great, wouldn’t it? And I was going to be asking you to play with me,” McCartney told Swift when they met up recently. “Were you going to invite me?” she responds. “I was hoping that you would. I was going to ask you.” He reveals his thwarted plan: “I would’ve done ‘Shake It Off.’ …. I know it, it’s in C!”

Instead, they ended up teaming up for a different kind of collaboration — a charmingly intimate in-person conversation and cozy, sweater-filled photo shoot at McCartney’s London office that is the basis for a cover story in the new issue of Rolling Stone. The special edition is a “Musicians on Musicians” issue that also features conversations between pairings like Lil Baby with Lil Wayne, Elvis Costello with Iggy Pop and Future with Roddy Ricch.

Swift is said in the introduction to the article to have arrived at McCartney’s place without a team, doing her own hair and makeup for the photo shoot conducted by the ex-Beatle’s daughter, Mary McCartney, and describing the trip overseas during quarantine as “feel(ing) like a rare school field trip that you actually want to go on.”

The ostensible subject matter is comparing notes on the albums both stars made during lockdown, her “Folklore” and his upcoming “McCartney III,” though plenty of other personal anecdotes enter in amid the comparisons on songwriting and recording techniques.

Swift talks about the few times they’ve been together at parties, at which either might be inevitably cajoled into an impromptu performance. McCartney remembers Swift singing Foo Fighters’ “Best of You” at one such intimate confab, eventually egged on by Dave Grohl. “I was playing it on piano, and he didn’t recognize it until about halfway through,” she says. McCartney recalls a party at which “I seem to remember Woody Harrelson got on the piano, and he starts playing ‘Let It Be,’ and I’m thinking, ‘I can do that better.'”

Swift discusses working with Aaron Dessner on what was not initially conceived as a 2020 release. “It turned out he had been writing instrumental tracks to keep from absolutely going crazy during the pandemic as well, so he sends me this file of probably 30 instrumentals, and the first one I opened ended up being a song called ‘Cardigan’…  He’d send me a track; he’d make new tracks, add to the folder; I would write the entire top line for a song, and he wouldn’t know what the song would be about, what it was going to be called, where I was going to put the chorus.I had originally thought, ‘Maybe I’ll make an album in the next year, and put it out in January or something,’ but it ended up being done and we put it out in July. And I just thought there are no rules anymore, because I used to put all these parameters on myself, like, ‘How will this song sound in a stadium? How will this song sound on radio?’ If you take away all the parameters, what do you make? And I guess the answer is ‘Folklore’.”

McCartney says he was similarly loose with his new album. “It’s more music for yourself than music that’s got to go do a job. My thing was similar to that: After having done this little bit of film music, I had a lot of stuff that I had been working on… and it’d be left half-finished. So I just started saying, ‘Well, what about that? I never finished that.’ … And because it didn’t have to amount to anything, I would say, ‘Ah, I really want to do tape loops. I don’t care if they fit on this song, I just want to do some.’ So I go and make some tape loops, and put them in the song, just really trying to do stuff that I fancy. … I had no idea it would end up as an album; I may have been a bit less indulgent” if that had been the plan, he admits.

They discuss the freedom of using pseudonyms on occasion. McCartney brings up having used the name “Bernard Webb” to write for Peter & Gordon (as well as his “Fireman” moniker for more experimental work), just as Swift talks about becoming “Nils Sjöberg” to work on a song for Rihanna.

The two are philosophically in agreement about playing the hits at their stadium shows. Swift brings up being thrilled to hear an inordinate number of McCartney’s smashes at a show in 2010 or 2011. “I think that learning that lesson from you taught me at a really important stage in my career that if people want to hear ‘Love Story’ and ‘Shake It Off,’ and I’ve played them 300 million times, play them the 300-millionth-and-first time. I think there are times to be selfish in your career, and times to be selfless, and sometimes they line up. … I just remembered feeling that bond in the crowd, and thinking, ‘He’s up there playing these Beatles songs, my dad is crying, my mom is trying to figure out how to work her phone because her hands are shaking so much.'”

“I’m glad that set you on that path,” McCartney responds. “I understand people who don’t want to do that, and if you do, they’ll say, ‘Oh, it’s a jukebox show.’ I hear what they’re saying. But I think it’s a bit of a cheat, because the people who come to our shows have spent a lot of money. We can afford to go to a couple of shows and it doesn’t make much difference. But a lot of ordinary working folks … it’s a big event in their life, and so I try and deliver. I also, like you say, try and put in a few weirdos.

Swift says “Folklore” represents the first time she has written in character and tells him about the real-life figure that inspired “The Last Great American Dynasty.” But when McCartney asks if the song “Peace” is a character song, too, she responds that that one is about “being in the relationship I am in now, I have definitely made decisions that have made my life feel more like a real life and less like just a storyline to be commented on in tabloids. Whether that’s deciding where to live, who to hang out with, when to not take a picture — the idea of privacy feels so strange to try to explain, but it’s really just trying to find bits of normalcy. That’s what that song ‘Peace’ is talking about. Like, would it be enough if I could never fully achieve the normalcy that we both crave?”

The conversation then explores McCartney’s own efforts to have a normal life, saying, “Maybe I should have, like, a big stately home. Maybe I should get a staff. But I think I couldn’t do that. I’d be so embarrassed. I’d want to walk around dressed as I want to walk around, or naked, if I wanted to.”

“That can’t happen in Downton Abbey,” quips Swift, eliciting a laugh out of McCartney.

Read the entire Rolling Stone conversation here.