Many of the photos in Terry O'Neill's collection were taken in the late '60s at a point when Sinatra should have started to look like a complete dinosaur. He represented a strange era when presidents, singers, mafioso, prizefighters and literary sensations all hung out together and did God knows what behind closed doors.

Whereas the new generation of rock 'n' rollers used their talents to rail against the system, Sinatra used his voice to get power and influence within the system.

While Jim Morrison, Janice Joplin and Keith Richards were doing whatever they wanted and to hell with the older generation, Sinatra did what he wanted because he was the older generation (and he was sharing girlfriends with JFK while he did it). As Gay Talese wrote in his seminal Esquire article "Frank Sinatra Has a Cold", Sinatra was "the embodiment of the fully emancipated male, perhaps the only one in America, the man who can do anything he wants, anything, can do it because he has the money, the energy and no apparent guilt".

That's why any good snapshots of Sinatra are special. We feel we're getting a glance at a world we're not permitted to glance at.

Englishman Terry O'Neill got his first break at the photographic unit at Heathrow Airport when by chance he snapped a sleeping RAB Butler, home secretary in Harold Macmillan's government.

He found work with the Daily Sketch in 1959. Over the course of the '60s he photographed members of the British royal family, the Rolling Stones and The Who, and has taken intimate portraits of Sean Connery, Audrey Hepburn and Brigitte Bardot (he spent three years married to Faye Dunaway somewhere in the middle of all that).

He made his reputation catching celebrities in moments of quiet relaxation, but the idea that these photos are candid seems quaint by today's standards.

Collected after a long period following the star in the '60s and '70s, these monochrome images, collected together for the first time here, conjure up a lot of the charm, charisma and work ethic of their subject. . . but they're hardly tabloid fodder.

O'Neill has a fascinating insight into the party line, but it's still the party line . . . Sinatra charming Raquel Welch, Sinatra in spectacles working on arrangements, Sinatra laughing with Count Basie, Sinatra holding forth on stage. There are photos that seem to hint at something brooding beneath the surface, but it's just a hint . . . Sinatra on the boardwalk with a goonish looking entourage, Sinatra looking weary after a show. None of these contradict Frank the archetype.

And, let's face it, would we really want them to?

1 Sinatra laughing at the piano All work and no play makes Frank a dull boy. When people talk about candid shots, this is really what they're talking about. You can't pose or fake a laugh. When a photographer like Terry O'Neill has 'privileged access' to someone like Sinatra, he uses this privilege to perpetuate the image Sinatra wants to project, not to get a shot of Sinatra's gusset as he drunkenly exits a car in a mini-skirt. So in that sense O'Neill was embedded.

There are no shots of Sinatra before he puts his hair-piece on.

There are no shots of Sinatra in a rage at an underling. There are no shots of Sinatra with a ruffled shirt or crinkled clothes. However, a photo like this really brings out the humanity in a way that a scurrilous story on Popbitch or a nipple incident on the pages of Heat magazine leaves well and truly behind.

2 Sinatra lights a cigarette in front of a portrait of Raquel Welch This is a great image of Sinatra lighting a cigarette in front of a painted image of Raquel Welch on the set on the 1968 film Lady in Cement. The picture of Welch is just the kind of 'tasteful' image one imagines a guilt-free swinging bachelor would have in his love-den in the late 1960s.

Sinatra had his pick of ladies from the early 1940s when he toured with Tommy Dorsey's big band, but I suspect what he really wanted was a nice perfect picture of one. After a traditional Italian marriage to a perfect matriarch, Nancy Barbato, he had a failed marriage to Ava Gardner, whom he adored, and at this point in his career, according to his manservant George Jacob's tell-all biography, he was pretty much doing what he wanted with the ladies. He followed this with a third marriage to Mia Farrow and a fourth to Barbara Blakely Marx. "He adored women, " says Terry O'Neill. "They were all ladies to Frank. He said, 'I'm supposed to have a PhD on the subject; I admire them. But like all men, I don't understand them.'" Online I found a fansite which insists Frank hated women who drank too much, smoked or ate lamb, probably because these factors made them even more incomprehensible.

3 Frank collects his thoughts before going onstage Sinatra had a relentless professionalism and work ethic. He would often do whole concerts after a full day on a film set and he was always "on" when he needed to be on (although he could be a cranky git at other times). The travel box and shoes you can see through the door give the sense that he's a hardtouring musician who may even have carried them up there himself, whereas in reality, at this stage of his career Frank had to carry very little, leaving it all to the reliable crew of ex-prize-fighters and failed actors who followed him everywhere. But cynicism about Sinatra and his motives disappear as soon as he opens his mouth on stage.

There's a great bit in "Frank Sinatra has a cold" when after 15 minutes of bitching about technical hitches before a TV rehearsal, he starts to sing and everyone just stops to listen.

4 Sinatra performing The master on stage . . .

Terry O'Neill notes that when the Chairman of the Board was performing he never seemed to exude an ounce of effort, but when he came off-stage he often crumpled with exhaustion. A newer generation preferred to see people like Jim Morrison and Iggy Pop practically disintegrating on stage, but Sinatra was all about cool and composure. A performance was just that, not a breakdown by another name. A good rock concert is all about being out of control. Sinatra always stayed holding the reins.

5 Sinatra being knocked over in an onset stunt Another image from the set of Lady in Cement. By all accounts Sinatra was happy to do a lot of his own stunts even when they could have been done by a double. Which is just as well, if someone had really knocked Sinatra over like this I wouldn't fancy their chances against the feudal system of acolytes which surrounded him on a daily basis. But Sinatra had a lot of loyalty to the film business and was willing to do anything for a good shot. Film had resurrected his career after it slumped in the early '50s. He had been dropped by both Columbia and MCA in 1952 when a starring turn in From Here to Eternity brought him back from the abyss. So although music was his first love and the art he took most seriously, he never underestimated the power a good movie could have on his career (although he hated doing more than one take).

6 Sinatra walks along the boardwalk with his entourage Frank had a 'crew' well before Afrika Bambaataa invented hiphop (on a wet Tuesday in 1977).

And part of being a crew is how to walk as a crew, as demonstrated in this picture. Pace is crucial . . .

placing yourself in the centre of an entourage is difficult enough when strolling with only one or two people but Frank seems to manage it. You also need a 'regal bearing' which enables you to gaze off into the middle-distance. This picture is great because it puts us, the viewer, in the position of one of the regular Joes and Jills sitting around on the boardwalk.

Sinatra knew the intimidating effect a group of large men could have on a boardwalk or bar, so a number of his key personnel were big intimidating men . . . Al Silvani, a boxing manager, was his wardrobe man; Ed Pucci, a 300lb football lineman, was his aide-de-camp;

Brad Dexter an unsuccessful actor, became a glorified security man after saving Sinatra from drowning. "I'd kill for him, " he said to Gay Talese in 1966. The sycophancy was probably unbearable. Sinatra's favourite comic Don Rickles used to joke about how members of the entourage would look at Frank to check whether to laugh.

7 Sinatra with Pat Henry in drag No this isn't that 'Sinatra uncovered' shot we were all hoping for, but another film shot.

This time it's with the comedian Pat Henry dressed as a woman.

According to O'Neill, taking photos from the wings, between each take the two alpha-males would rag and banter with each other but as soon as the camera was rolling Frank would slip straight into character again.