He soon released a solo album that reached No 1, then formed Wings with his wife and Denny Laine of the Moody Blues. The band had a dozen top ten hits and were a big force throughout the Seventies.
Since then he has had a formidable solo career as a pop singer, collaborated with the likes of Stevie Wonder, Michael Jackson and Super Furry Animals, appeared on Broadway, written an oratorio and won four Grammy awards.
He is a fellow of the British Academy of Songwriters, Composers and Authors, an officer of the Légion d'Honneur, and a knight bachelor of the United Kingdom. He is also Britain's wealthiest musician - sharing a £710m fortune with his third wife Nancy, according to the latest Sunday Times Rich List.
There is quite a lot more to James Paul McCartney than the fact that he was once a Beatle, and there are few on the planet who don't know who he is.
Yet whenever he does anything that makes the newspapers, he is invariably described as "former Beatle" or "Beatle legend".
This week he was taken to hospital in Japan and every one of the six papers that reported the fact felt the need to refer to the Beatles - even those that had only 50 or 60 words to play with. Most of the people writing these stories hadn't even been born when the Beatles ceased to exist.
If someone is unknown to most of the world, some description is necessary. If they are known in one sphere and being reported on for activities in another, it is good to refer back to their "home territory". If they are a member of a better-known organisation - the singer in a band, perhaps - it is fair to put in a shorthand descriptor.
But some people and organisations transcend this: the Queen, Cliff Richard, the BBC, the RAF - Macca.
Even if he didn't, why talk about what he used to do rather than what he does now? Shirley Temple-Black, the "former child star" in the context of her ambassadorial work? Arnold Schwarzenegger, the "former Mr Universe"? David Beckham, the "former Manchester United footballer"?
The Beatles were a seminal group; they ushered in the Sixties and all that followed musically. When McCartney dies, that ten-year period of his early life will figure prominently at the top of his obituaries.
But for now he is alive. He is a 71-year-old man who still draws huge crowds to hear him play, a man whose songs are being sung around the world every day of the year. He is a songwriter, musician, philanthropist, campaigner, father (and no, we don't find it necessary to mention her dad every time we write about Stella's designs).
So let's recognise him for what he is, not what he was. And stop telling people what they already know.