Winter's come early and people are dreaming of escape. Those who fancy a shot of African warmth in these chilly times, but without boarding a plane, should head to the National Theatre, where a chunk of London's South Bank has been transformed into a fabled slice of Lagos. The show is Fela!, telling the story of Fela Kuti, the Nigerian musician, impresario, womaniser and all-round legend who invented a whole new style: Afrobeat. In the telling, the theatre has been transformed into Fela's downtown Lagos nightclub, the Shrine.

The combination of throbbing music, breathless dance, gorgeous costume and a 24-carat star in Sahr Ngaujah does a masterful job in transporting its audience a continent away. And yet later I found myself thinking of a wintry day somewhere else entirely, an event whose 30th anniversary falls next week: the death of John Lennon.

Musically, the two men were worlds apart. What they had in common is something, now almost gone, which once seemed almost automatic in pop music – a commitment to politics.

Fela Kuti may have started out playing highlife and jazz in 1950s London, but, thanks to a spell in Los Angeles, where he was exposed to the Black Power movement, he returned to 1970s Nigeria not only with a new sound but a new message. In the Shrine, from the wee small hours of the morning until dawn, he would offer not just African rhythms but Africanist doctrine, urging black pride and a return to indigenous African religious custom. He would rage against colonialism and lament the disappointments of post-independence. He railed against Africa's homegrown rulers as well as the multinational corporations who had picked up where the old imperialists left off.

On stage Fela gives an impromptu lecture comparing the colonists of old to house guests: "At first it's quite nice having new faces around. But then you start noticing things going missin'. Ashtrays. Towels ,  Petroleum. Diamonds. People! And what do they leave in return? Gonorrhea and Jesus."

Fela Kuti's politics were full-frontal; he posed a direct challenge to the authorities, twice trying to run for president. He was regularly arrested, jailed and beaten for his dissent. In one raid on his compound, his mother was thrown from a first floor window to her death. And all the while, he made his case through music. The 1980 song International Thief Thief names corporate names: "Pipeline broke/Shell oil cries/Prices rise/Police break head/Blood dey flow , "

John Lennon was never imprisoned or tortured, but he was seen as a threat. Along with MI5, the FBI assembled some 281 pages of material on him, monitoring and transcribing his TV appearances, checking out his friends. In 1972 the incorrigibly paranoid Richard Nixon worried that the former Beatle's support for his Democratic opponent might deny him a second term in the White House: so Nixon unleashed the Feds, who plotted an attempt to get Lennon arrested on drugs charges.

They weren't wrong to think the man who once shook his moptop like a wind-up toy was radical: he was. In Give Peace a Chance and Happy Xmas (War is Over) he had written not one but two anthems of the movement to end the Vietnam war. His politics hardened in the immediate aftermath of the Beatles' breakup, declaring after Bloody Sunday that in a choice of the British army or the IRA he would side with the IRA. Those raised in the post-Good Friday era might not realise quite how rare such a statement was in the early 1970s, to say nothing of the bouquet of red roses and £5,000 cheque John and Yoko sent to the Clydeside shipworkers in 1971.

Again, as with Fela, it was the music that counted. Lennon may have given money to the IRA, but his songs Sunday Bloody Sunday and Luck of the Irish probably helped more. The same goes for his stance against apartheid – the Beatles were early in their refusal to play in South Africa or in the segregated states of the American south. He engaged with the 1968 protests, though initially drew the line at violence: "Don't you know that you can count me out," he sang in Revolution. He was alive to class politics – think Power to the People and Working Class Hero – and was quick on to feminism, embracing a fairly hardcore analysis in the problematically titled Woman is the Nigger of the World.

Those two careers are celebrated now: Fela's songs live anew at the National while the Lennon oeuvre has been remastered to mark what would have been his 70th year. Their music sounds as urgent as ever. And yet their politics makes them figures from a bygone age. Today no governments are shaken by the music of Snow Patrol; the FBI will not be taking out a file on Gary Barlow. These days popstars who speak out are rare and seldom make much impact. Why?

Any explanation has to begin with the times. Lennon can't be wrenched out of context: the 1970s, when he was at his most active, was an intensely political period. He sang about Revolution; many thought one was on the way. Fela's career straddled a tumultuous period in Nigerian history, from empire to independence to dictatorship.

But music has changed too. "Pop has become a victim of its own success," says Jon Savage, historian of the genre. When pop music erupted more than a half century ago, it burst out of the fringe, rendering it automatically countercultural. Now it is fully absorbed in the mainstream. For Savage, final proof came the day Prince's new album came free with a copy of the Mail on Sunday. Others cite the use of Janis Joplin's anti-materialist anthem Mercedes Benz in an ad for ,  Mercedes Benz. The process of co-option happens at warp speed now. The xx had barely made their name before their Intro was snapped up by AT&T's admen. As for the once threatening John Lennon, a whole generation of kids know him now only as the name of Liverpool airport. Slogan: Above us only sky.


Of course there are exceptions. Bono is politically active, campaigning against poverty. But images of him palling around with George W Bush, or praising Brown and Blair as the new Lennon and McCartney, as well as accusations of tax avoidance levelled by aid organisations against U2, cast him as a rather establishment kind of campaigner.

Here's where the media should put its collective hand up. Any musician who dares talk politics today risks mockery. Witness the evisceration of Sting and his rainforest campaign. One only has to imagine how the Guardian's own must-read Lost in Showbiz column would monster a Lennon today for daring to talk of a world with no possessions – even as he cleared space in his second New York apartment solely for the storage of Yoko's fur coat collection.

And yet the political popstar may not be gone forever. There was a revival in the 198os, a time when pressure on the young increased. We could be living through just such a time now, whether it be tripled tuition fees or an unemployment rate among 18- to 24-year-olds of 17.1%, nearly 10 points higher than the rate for the workforce as a whole.

If musicians turn into protesters, the establishment will tremble a bit, but they need not quake. Greats like Fela and Lennon can truly shift the attitudes of a generation, but often political pop becomes a handy safety valve. As one pop historian puts it: "The Germans had Baader-Meinhof, we had punk." The truth is, it's not a choice of either music or politics: both Fela and Lennon showed you can have both.

The Ultimate!!!

Yeah bro, the greatest of all time.

i loved them both, they were both geniuses.

Dedicated, sincere and iconic my their souls rest in peace

Yes may their loving soul rest in perfect PEACE