The Terms of Paul McCartney’s Guest Appearance on ‘The Simpsons’ Changed Lisa’s Character ‘In Perpetuity’

Much like Strawberry Fields, vegetarianism is forever.

In the floating timeline of The Simpsons, so many character traits, hobbies, interests and epiphanies have taken over an episode only to disappear from the canon as soon as the credits roll. By now, I’m pretty sure that Homer has worked every single job recognized by the Department of Labor and then some, and poor little Lisa, so often relegated to the role of the preachy, liberal, self-righteous self-insert of the writers’ room, has adopted each and every social issue of which the average Twitter user would be well-aware as her hill to die on. However, not unlike Bleeding Gums Murphy, Lisa’s more specific convictions typically make a grand entrance and a premature exit to the disappointment of her more principled fans — including Paul McCartney.

The Beatle made one of the most memorable guest appearances in Simpsons history during the landmark Season Seven episode “Lisa the Vegetarian,” wherein, as the title suggests, the Simpsons’ middle child swears off meat after a life (and canon) changing trip to a petting zoo. But McCartney and his wife only agreed to appear in the episode on the condition that both Lisa and her writers truly and permanently committed to the dietary decision. Said McCartney in a 2020 interview for GQ, “We were a bit worried that she would be a vegetarian for a week, then Homer would persuade her to eat a hot dog.”

“The producers of the program assured us that she would remain that way, and they kept their word,” McCartney said of his agreement with The Simpsons over its most animal-friendly second grader.

According to Simpsons producer, showrunner and current story consultant David Mirkin, McCartney’s condition for appearing on the animated series all the way back in 1995 was much more than a handshake deal, too. Earlier in 2020, Mirkin told The Radio Times that, though McCartney couldn't be bothered to keep watching The Simpsons so long past the Golden Age, he’s kept his word in making sure that Lisa kept hers. “He always checks,” Mirkin said of McCartney’s monitoring of Lisa’s dietary habits. “And he’s always surrounded by nine or 10 lawyers, so it’s quite frightening.”

Presumably, this means that Lisa’s vegetarianism is a legal matter that McCartney negotiated all the way back in Season Seven, which makes the episode “Ae Bonny Romance” from this past Season 35 potentially problematic. In the episode, Lisa attends the Edinburgh Fringe Festival and eats a Scotch egg, which is a breaded, deep-fried soft-boiled egg coated with sausage meat. Presumably, the current writing staff didn’t know that Scotch eggs aren’t vegetarian and chose the food because, well, Scotland, but time will tell if McCartney’s lawyers will accept “too lazy to Google ‘Scotch egg ingredients’” as a legal defense.

It’s a shame McCartney didn’t make The Simpsons commit to Lisa learning the lesson Apu taught her in the pivotal scene about how “you can influence people without badgering them always.” Imagine how many times he’d have to sue The Simpsons for that one.