I'm getting a little worried about Sir Paul McCartney. He seems determined to reinvent himself, or at least to edit the picture of him that's held in the public consciousness.

It was five years ago that Sir Paul informed the readers of Uncut magazine that it was he, the supposedly clean-cut, chirpy one of The Beatles, who had first tried heroin in the 1960s, although "it didn't do anything for me". Meaning, "I'm dead wicked, me, but I'm also too tough to be a casualty." He was also the first Beatle to admit to dropping LSD, an admission that always irritated John Lennon, who preferred to keep the outlaw role for himself. He used to call McCartney "Engelbert Humperdinck" to slag off his status as housewives' pin-up.

Now McCartney has been polishing the self-portrait again in a bid to establish intellectual-political bona fides. In an interview in January's Prospect magazine, out tomorrow, he reveals that it was he who radicalised The Beatles in the mid-1960s by bringing Vietnam to their attention, after he'd met Bertrand Russell at his house in London. Russell, a leading pacifist for decades, told the clueless musician "about the Vietnam war – most of us didn't know about it, it wasn't yet in the papers – and also that it was a very bad war". Whereupon McCartney went back to Abbey Road to tell "the guys, particularly John, about this meeting, and saying what a bad war this was". A bad war, rather than one of those thoroughly decent wars of which most people approve.

From this, we are invited to infer, the Beatles' later anti-war protests about love, peace, war and revolution must have sprang. Yes, it was Lennon and Yoko Ono who brought out "Give Peace a Chance" and "Happy Xmas (War Is Over)", and, yes, McCartney's only political song was "Give Ireland Back to the Irish", but it was he who, you know, had the political conscience first.

It's the detail about Bertrand Russell that makes one sceptical about Sir Paul's retrospective conversion. It wasn't any ordinary bloke who alerted him to the Vietnam conflict, but one of the world's great philosophers. Of course, McCartney is himself so eminent now, he would expect to be briefed on world events only by the global A-team. He exists in a heady stratosphere of Olympian fawning.

According to the journalist Mark Edmonds, there was trouble in Washington a few years ago when McCartney visited the White House and autographed a book for Colin Powell, but not for the President, George Bush senior. An aide had to be sent to buy a second copy, to be signed. And when Sir Paul played a concert in Red Square, Vladimir Putin invited him to stay as long as he fancied at the Kremlin (he accepted a cup of tea and a guided tour). No wonder he feels he can write hectoring letters to the Dalai Lama, complaining that the Lama eats meat, thus contradicting his Buddhist belief in not causing suffering to animals. He is empowered by fame, by destiny, by history itself.

Later in the Prospect interview, McCartney says that "Eleanor Rigby" owes a debt to his English teacher, Alan Durband, who introduced him to Chaucerian bawdy and gave him a passion and a feeling for structure. Durband had been tutored at Cambridge by F R Leavis, and his bracing, Leavisite views on literature enthused the young Paul. "So there is me," McCartney muses, "getting this Leavis-Durband lineage..."

So Paul McCartney not only wrote songs in the 1960s, he energised a whole generation to protest against Vietnam, because he learnt about it at the knee of Bertrand Russell, the most famous anti-war protester in England; you'd think that, in a way, a torch was being passed from one generation to the next. Moreover, some of his melodies were influenced by F R Leavis, the leading Oxbridge academic of his generation; you'd think that, in a way, a torch was being passed on... And far from being a clean-cut goody-goody, he was in fact a crazy, drugged-up rebel-outlaw-tearaway, despite morphing, more recently, into the ultimate Man of Virtue and Piety, who casually ticks off leading Buddhists for their cruelty to animals...

What an extraordinary cat's cradle of self-invention. If we learn in the future that McCartney also invented the Pill and the sky-ray lolly, or that T S Eliot begged him, in 1962, to collaborate on Four More Quartets, I won't be surprised.