When the saxophonist Sonny Rollins played last year's London Jazz Festival, he was 79 years of age. For this year's event – which starts on Friday – he'll be 80. It's a logical enough progression, but Rollins is such a legendary figure that his birthday celebrations have ended up defining much of the festival's overall character. For this is the year of the oldies but goodies, and some of them make Rollins look like a teenager.
Take the singer and lyricist Jon Hendricks, the man Time magazine called "the James Joyce of jive". Although Hendricks turned 89 last month, he can be seen doing his energetic nightclub act for three evenings in a row at Ronnie Scott's in Soho. Or Juliette Greco, the queen of chanson, who's now 83. You can argue over whether Greco is jazz or not (and whatever you decide, she did have a long-standing love affair with Miles Davis), but she is currently performing with a quite shocking power and passion. Indeed, her repertoire even includes a little Arabic hip-hop. Dame Cleo Laine, who was 83 last week, is a bit unsteady on her pins these days, but her voice remains astonishingly strong and expressive. She also embodies the whole post-war era in British jazz, all the more so since the death of her husband, Sir John Dankworth, earlier this year.
Relative youngsters such as the saxophonist Charles Lloyd, who's 72, the trumpeter Hugh Masekela, 71, and the pianist Herbie Hancock, 70, reinforce the sense that this year's festival is – in a famous jazz phrase – conversing with the elders.
And if any more evidence was needed, take the case of the Barbican's gospel stars, the Golden Gate Quartet, who appeared at the famous Carnegie Hall From Spirituals to Swing concert in 1938. There are no original members left, but the leader, Clyde Wright, has been with the band for 56 years.
Of course, in jazz this question of age is not really about geriatrics, the sprightly over-eighties, or sentimental backward glances at all. It's about history, and about tradition. There's an inescapable sense that once the present heroic older generation passes on, the meaning of jazz will never be the same again.
The range of experience the musicians draw upon is unrepeatable: Greco saw her family taken off to a Nazi concentration camp (they survived to be repatriated in 1945); Masekela's life and career have been defined by the cruelty of Apartheid; the super-sensitive Lloyd grew up amid the vicious segregation of Tennessee. Both Rollins in the US and Laine in the UK had to fight against racism and demeaning stereotypes.
And jazz itself is changing. These days, musicians learn about bebop and cool in seminars at college, rather than the informal master and apprentice system that has governed jazz since its birth. "It's too fast and too hard on young musicians these days," the jazz pianist Keith Jarrett told me. "They become famous too fast and leaders too soon. They don't get a chance to work with great players – the few of whom are left are mostly old and dying. They listen to records too much and think they are the real thing, but records are exactly what the word suggests: they're documents, a sign, a pointer towards the real thing, but not the thing itself."
For Theodore "Sonny" Rollins, who was born in New York's Harlem to parents from the Caribbean, the tradition was out there on the block. As a child, he could take a glossy publicity picture a few steps round the corner and get the great saxophonist Coleman Hawkins to autograph it. "When I was a boy and went to the Apollo Theatre, there'd be that moment when the curtain would open and you'd see and hear the band for the first time and it would always be a spectacle," he remembers. "I was fortunate when I was starting out because jazz was really firing. We had Billie Holiday, Charlie Parker, Lester Young, [Duke] Ellington and [Count] Basie, everybody performing at the same period, and that really is a golden age. You have to be careful not to be too hard on the present time. The music goes in stages and ages and I'm sure there will be another golden age."
Although one can't pretend that a Rollins performance today is as energetic as it once was, he is still playing with remarkable vigour. There are compensations, too: where once Rollins was Hamlet, now he's King Lear. He's not coasting, either: for his sold-out 80th birthday concert at the Barbican on 20 November, Rollins will be leading
a new band. "I'm getting older and I can't do a real heavy schedule any more, so when I do play a concert I put a lot into it physically and mentally. That's just the way I am, and I can't really do any more."
He also continues to set new personal goals. "Mainly, if it were at all possible, I'd like to really improve what I'm doing and play better. I still think that there are solos that will bring new revelations."
Juliette Greco, 83
"Inside I'm the same woman. Outside, no, because the years are passing and I can't help it. There's no magic rubber. But I'm doing what I'm in love with and I'm very happy in my work. No one knows about my life, they stopped disturbing me many years ago because they knew it wasn't possible to catch me out – with whom is she going to bed? What is the interest in that? It interests me, but I am the only one, or maybe two. I go my own way."
Greco met Miles Davis in Paris in 1949, when he was 23 and she 22. "He was a marvellous man, handsome, a beauty. Something came between us, but that happens. I was very surprised when I went to New York and realised that he was black. I had never thought of him as black before, not that it changed my mind. But it was a good thing that he went back home, as his work was there. We never really broke up. He was always there, right through his life until the end."
An Evening With Juliette Greco, Barbican, London EC2 (tel: 0845 120 7550, barbican.org.uk), 21 November
The Spiritual Seeker
Charles Lloyd, 72
"I haven't become good enough to quit yet," says saxophonist Lloyd. "I'm still a tone-seeker, and my sound is all. If you don't have a beautiful sound you can play all the notes in the world and they won't mean anything."
After moving from Memphis to New York, Lloyd became a star of flower-power jazz in the 1960s; the Beatles attended his concerts and he shared stages with Janis Joplin and the Grateful Dead. "I was too late to hang out with Lester Young, whose tenderness and vulnerability are very dear to me, but I got to spend time around Duke Ellington and Billy Strayhorn. Being born in the South, I had to have strength to rise above rejection. When I was a little kid in Memphis, I used to cycle past [the pianist] Phineas Newborn's house. You'd hear him playing Bach from out the door and I'd just roll on the floor and drool. The tradition is a direct link to the infinite, you go soaring. I'm still a 72-year-old kid, a junior bringing up the rear. All of us are in service."
The Charles Lloyd Quartet, Barbican (details as before), 17 November
Cleo Laine, 83
The UK's greatest jazz vocalist over the past half a century, Laine auditioned for bandleader John Dankworth in 1951, and married him seven years later. Together, they became husband-and-wife stars who, uniquely for British jazz, were as popular in America as they were at home.
"Travelling gets more difficult these days," says Laine, who continues to tour America. "There are such long waits at the airport, while once upon a time it was no harder than getting on a bus. Today, one is never sure if the plane is going to be there to get on, and my knee replacement keeps setting off the metal detectors, which is very ageing. But being a dame means that sometimes you do get looked after a bit more, and that makes it easier.
"I've always made up little dramas when singing songs," she says of the lyrics she continues to write. "Of course, these dramas change depending on what is going on in the world and my life. Obviously, this affects the storytelling. Sometimes it's sad, sometimes happy, you never know from day to day."
Cleo Laine, Barbican (details as before), 16 November
The Freedom Fighter
Hugh Masekela, 71
Trumpeter Masekela was given his first instrument by Father Trevor Huddlestone, the anti-Apartheid chaplain at his secondary school. Later, he was given another by Louis Armstrong. He left South Africa after the Sharpeville massacre in 1960, and John Dankworth and Yehudi Menuhin helped him get into London's Guildhall School of Music.
Encouraged by Harry Belafonte to study in the US, he later played with the Byrds and recorded the four-million-selling single "Grazing in the Grass". In the mid-1990s, Masekela returned to live in South Africa.
"I still practise every day whenever I can," he says. "With age, you get better on any instrument if you practise. I hope I am getting wiser, but in this age of technology, wisdom is relative. Besides, it would be very presumptuous to think of myself as wise.
"Apartheid has taught me that freedom isn't necessarily democracy. An oppressed people do not necessarily change with change; the privileged resent losing their privileges, the bigoted have a hard time trying to learn goodwill and charity. The right-wing never sleeps."
Hugh Masekela, Royal Festival Hall, London SE1 (0844 875 0073, southbankcentre.co.uk), Friday; Masekela then tours the UK until 20 November. See musicbeyondmainstream.org uk for details