The Beatles legend Sir Paul McCartney, 77, famously made a guest appearance in an episode of The Simpsons. The Hey Jude singer and his late wife Linda McCartney did a voiceover in an episode, which saw Lisa stop eating meat.
But Paul’s appearance on the popular animated show came with a stipulation that The Simpsons producers had to follow, according to the show’s consultant David Mirkin.
Speaking in a candid interview in this week’s Radio Times magazine, he revealed the show staff had to make a specific “promise” to the legendary star which they still follow today.
David explained that Paul wanted main character Lisa Simpson to remain a vegetarian on the Channel 4 programme.
He remarked: “When I asked him to do the vegetarian episode, he agreed but made me promise to keep Lisa as a vegetarian — and I was happy to comply, because I’m a vegetarian, too.
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Sir Paul McCartney alongside his late wife Linda McCartney
“Every time I see him, he always checks — and he’s always surrounded by nine or ten lawyers, so it’s quite frightening!”
Fans may recall Lisa the Vegetarian episode of The Simpsons, which aired in 1995.
In the episode, Lisa decides to stop eating meat after bonding with a lamb at a petting zoo.
Her schoolmates and family members ridicule her for her beliefs, but with the help of Apu, as well as Paul and Linda McCartney, she commits to vegetarianism.
Paul McCartney appeared in an episode of The Simpsons
Sir Paul McCartney shared a picture of his mum on Mother’s Day
The episode makes several references to Paul’s musical career, and his song Maybe I’m Amazed plays during the closing credits.
David’s comments comes after The Simpsons turns 30-years-old in December.
It is the longest-running American scripted prime-time series and has aired over 672 episodes.
Elsewhere, Paul posted a touching throwback tribute for Mother’s Day on Instagram on Sunday.
His late mother Mary inspired the rocker to write the song Let It Be and she was the main breadwinner in the family with her career as a nurse and a midwife.
In view of his 2.9 million followers, the musician posted a black and white snap alongside his brother Peter and their mum.
The two young boys wore matching braces and smart shirts for the family portrait.
“Wishing Mothers all over the world a Happy #MothersDay – Paul #PaulMcCartney,” he captioned the image.
Fans flocked to comment on the post, as one person gushed: “Your mother would have been so proud.”
Another person remarked: “Look what your wonderful mother produced!”
“Oh wow. Wonderful photograph Paul,” a third person added.
It comes after the rockstar confided in James Corden, where he told him his mum was the inspiration for the iconic track Let It Be.
During an episode of Carpool Karaoke in Liverpool, Paul left James welling up over the emotional story.
“I had a dream in the sixties where my mum who died came to me in a dream and was reassuring me, saying, ‘It’s gonna be OK. Just let it be’.”
You can read the full interview in this week’s Radio Times out now.