Fom time to time in the summer months, small knots of tourists pause outside a nondescript building in a Soho alleyway. Today it houses television offices, but 25 years ago, history was made here. It was the home of Trident Sound, a studio where the Beatles once recorded.

The visitors, usually on a Beatles walking tour, seldom linger long. Trident was used only occasionally. The greatest hit recorded here was “Hey Jude. ” There are more important shrines to visit.

If those tourists had strayed back into the same Soho alleyway at the right times in recent months they might have caught, not echoes of the past, but the sound of a new chapter of the Beatles story taking shape.

In a cellar, only feet from Trident, skilled sound engineers have been working long into the autumn nights to put finishing touches to a six-part television history of the group.

This is the authorised version, funded by the three surviving former Beatles and by John Lennon’s widow Yoko Ono. It is told in their own words and features rare and unseen footage.

It is part of a dam-burst of memories and revelations about to flood our way. Also coming are several albums up to 180 songs drawn from archives and spanning the band’s brief collective recording career. These comprise demo tapes, alternative versions of familiar material and some unfamiliar songs. They will also include the much-heralded and controversial “new” Beatles records. These are two Lennon songs entitled “Free As A Bird” and “Real Love” which Yoko gave to the three remaining musicians in the form of rough demo tapes. Paul, George and Ringo have added the voices and instrumentation to transform them into Beatles recordings.

Also in production are video anthologies, a radio series, a book and, hint insiders, something even more eagerly awaited concerts somewhere, sometime soon.

Inevitably the whole circus will make a fortune, much from sales to those who came of age in the Sixties and for whom the Beatles music formed the soundtrack to their adolescence.

Their careers and solo recordings since good, bad or indifferent have attracted dwindling attention from that same generation. However the success of last year’s Beatles at the BBC collection proved that there are wells of interest that can still be tapped.

Remarkably, just as the exuberant music of the Fab Four soon seduced adult audiences in the 1960s so, today, it seems to have qualities that give it an appeal to a new young audience.

The latest generation to succumb to the Beatles magic is still in school. Girls like 11-year-old Cerys from Sheffield for instance. Her current favourites are a group called MN8, but she has been a Beatles fan ever since she saw a video of A Hard Day’s Night about four years ago. She likes John Lennon best because of his songs, but she also admits: “None of my friends like them so I have to pretend I don’t like them either.”

Down in Brighton another 11-year-old is also a fan especially of the older songs. Beatrice’s dad, once a musician, gave her The Beatles Songbook when she toddled to her early piano lessons. She’s been hooked ever since.

Older teenagers listen too. Stacey from London, for instance, who’s 18 and in his first job says: “They’re a bit like Blur or Oasis aren’t they? Good songs. It’s Indie bands that got me interested in the Beatles.”

Though they may be “just another band” to today’s young, it is remarkable that they still strike chords at all, something few of their contemporaries have managed 25 years on. The hype surrounding the most talked-of reunion in popular music begs the questions, why are they still so popular and do they still matter?

The musical influence of the Beatles is unarguable. Before them rock’n‘roll was scarcely a decade old and its significant achievements entirely American. We could manage only pale imitations of the blander stuff.

The Beatles changed all that. Nurtured on Liverpool’s passion for black rhythm and blues and hardened in Hamburg’s clubs, they coupled a uniquely urgent version of rock with sublime songwriting.

The marriage of Brian Epstein’s management and the musical midwifery of George Martin produced the most successful and influential musical aggregate the world has ever seen. For nearly eight years their restless creative urge opened up new musical vistas. The journey from the simple charm of “She Loves You” to the sonic strangeness of “Strawberry Fields Forever” took just four years.

Since then, generations of teenagers have aspired to replicate their achievements, hoping that handmade music and a recording contract would bring them a ticket to ride to the promised land. It is a resilient dream. Other artistes may match their sales and maybe their adulation. Better songs have and will be written. But the Beatles’ achievement will remain unique for reasons beyond their skill as musicians or performers.

The Beatles emerged in a world poised on the threshold of profound change. Post-war austerity was ebbing away and prosperity was in the air. The teenagers of 1963 were raised in an entirely different physical, political and mental environment from that of their modern counterparts. This was an age of optimism before Aids or terrorism, or the technological clutter and grim socio-political landscape of our times.

The band offered simple exhilarating paeans to the joys of life, love and youth. They cut across class lines, ignored prejudices and their early anthems still have power to pierce through today’s world-weary cynicism. The Beatles were at the birth of popular culture’s big bang their “yeah yeah yeahs” helping to usher it into life. Thirty three years after the first single, “Love Me Do”, their music is part of the background hum of a still-expanding universe.

Soon they found themselves riding a social revolution and developing a complex relationship to their time. They became emblematic of a deeper turbulence in the western psyche. Drugs and musical experimentation were clear signs of their fundamental shift to become counter-cultural prophets.

John Lennon once remarked that the Beatles were more popular than Jesus. For a time it seemed true. Idolised by millions, their work dissected and mythologised, they were courted by intellectuals and disapproved of by the establishment. Briefly their views, as well as their music, had the ear of the world and were taken very seriously. When they ditched drugs in favour of eastern mysticism a generation paused for deeper thought.

Composer Aaron Copland said: “If you want to understand the Sixties, listen to the Beatles’ music”. Poet Allen Ginsberg proclaimed Liverpool in 1967 to be “the centre of consciousness of the human universe.” And critic Kenneth Tynan thought the release of Sgt Pepper was as important a cultural event as the publication of T S Eliot’s poem “The Wasteland.”

Maturity created disharmony and disarray. Their unique compact eventually shattered and they fell to earth. John went on to dabble in avant garde art and radicalism before his untimely death. The others launched careers that seldom aspired to the Olympian heights of the 1960s. As the world moved on, the optimism of their era dissipated. The decade itself has become much-maligned retrospectively. Ian Macdonald, author of Revolution In The Head, one of the most perceptive books yet about the Beatles era, notes that: “Ironically the harshest critics of the Sixties are its most direct beneficiaries. The political voices of materialistic individualism.”

The Beatles story has grown stale in the retelling but we’ll soon discover if their own version of events will offer revelation or simply amplify familiar tales. In the process they may, nevertheless, offer reminders of the old magic, but it is unlikely to enhance their myth or appeal.

Quite why they’re doing it remains unclear. Interviewed by VOX magazine, McCartney said: “Just for the joy of getting together and doing something. We thought it would be a good idea, while we had some memory left, to try and remember the stories ourselves, to check them against each other and try and get something definitive down.”

Harrison meanwhile has always been more reluctant to acknowledge that history. He says: “Beatle George was a suit or a shirt that I once wore and the only problem is that for the rest of my life people are going to look at that shirt and mistake it for me.” While Ringo says: “There is nothing in the future for the Beatles, because there aren’t any Beatles anymore.”

So the coming deluge of music and pictures may, in the end, be a summation. Not the start of something new, but a long-awaited final chapter, leaving them free at last to slip the net of history and live the rest of their lives as ordinary people.

The Beatles Anthology will be screened on ITV from November 26

The Beatles Anthology 1 is released on all formats on November 21 by ParlophoneApple at around Pounds 20. The album also includes a booklet