First they were ours, for a brief and precious moment. Then, suddenly, they belonged to the world. Eyes of the Storm, the exhibition of Paul McCartney’s photographs at London’s newly reopened National Portrait Gallery, depicts with great clarity and special intimacy the handful of weeks in which the Beatles were transformed from a local celebration into a global phenomenon. Whatever their merits as art, McCartney’s hitherto unseen photos, taken between December 1963 and February 1964, record a pivotal moment in popular culture. The sequence of 250 backstage and off-duty images begins at the Liverpool Empire, a triumphant return home for the group during a UK tour reaching its climax at Finsbury Park Astoria in north London, where their 16-night Christmas variety show also features the actor Dora Bryan, recently in the charts with All I Want for Christmas Is a Beatle. Then, early in the new year, come 18 sold-out days and nights at the venerable Olympia music hall in Paris, playing two and sometimes three shows a day to a new generation of yé-yé fans at the top of a bill including acrobats and comedians. Within days they are in New York, appearing on the Ed Sullivan Show and conquering the hearts of a nation whose teenagers have, until this moment, been content to worship home-grown idols. As the Beatles travel on to snow-covered Washington DC and sun-kissed Miami Beach, I Want to Hold Your Hand is topping the US charts and the British invasion has begun. McCartney wasn’t a photographer, although later he would marry one, and later still a daughter of that marriage would become one. (His younger brother has also worked as a photographer, and Mike McCartney’s wonderful study of Paul and John Lennon playing acoustic guitars together, heads down as they work on a song, is part of this exhibition.) But Paul fondly remembers, as many of his contemporaries would, the experience of loading his parents’ primitive “Kodak box Brownie” with a roll of film good for only eight exposures, generally considered quite enough to record an entire postwar family holiday. In 1963, as Beatlemania swept Britain, and perhaps partly in retaliation against now being constantly confronted by the lenses of newspaper and magazine photographers, McCartney acquired a 35mm Pentax. Small enough to carry with him on tour, it enabled him to capture moments offstage with his bandmates and their entourage. From the ever-present professionals, he could solicit advice. Dezo Hoffmann, a Czech émigré who had flown with the RAF in the second world war and now worked for Record Mirror, was one; he had travelled to Liverpool to photograph the Beatles in 1962 and stayed close. Robert Freeman was another; he had recently been hired by Brian Epstein, the band’s manager, to take the striking chiaroscuro shot, influenced by French new wave cinema, for the cover of With the Beatles, their second album. Closer to their age, Freeman looked like he belonged in their gang. After McCartney’s films were developed, he marked up his favourite shots on contact sheets with a chinagraph pencil, as he’d watched the pros do. In the absence of the original negatives, lost over the years, many of the images in this show are printed from the contacts. Some softening is inevitable but unimportant; it suits the best of the black and white shots. Anyone would be proud of Paul’s image of Ringo Starr in a tricorn hat, taken during their stay in Paris, while his discernment is shown in the choice between two very similar shots of George Harrison: he selects the less obvious but more intriguing of the pair. Among those who pass before his lens are Epstein, faithful crew members Neil Aspinall and Mal Evans, Cilla Black, Paul’s girlfriend Jane Asher, David Jacobs, host of the special Beatles edition of BBC TV’s Juke Box Jury, and Sylvie Vartan, their co-star at the Olympia, and her boyfriend, Johnny Hallyday. The novelty of a first visit to New York is captured in shots of skyscrapers and NYPD officers on horseback, penning back the fans outside their hotel. In those innocent days their circle was relatively porous, with no permanent ring of personal security to guard them. Hence the presence of Murray the K, the soi-disant “fifth Beatle”, the radio DJ who had broadcast his show from their suite at the Plaza in New York and followed them to Miami, where he joined them by their hotel pool, in swimming trunks. There’s a quayside photo of Diane Levine, a pretty brunette who accompanied Paul to a drive-in movie in Miami. The convulsion set off by that short US trip is reflected in McCartney’s acquisition of colour film. Superficially, the results seem less “serious” – like going from character studies to holiday snaps. But the switch reflects a deeper sense of how their world was changing, almost overnight, as they took everyone along with them for the ride of a lifetime. Paul McCartney Photographs 1963-64: Eyes of the Storm is at the National Portrait Gallery, London, from 28 June to 1 October This article has been corrected: Mike McCartney is Paul’s younger, not older brother.