IT’S easy for me to define who the two most important men in my life are: my father and Frank Sinatra.

The former, well, I’m still taking a voyage round him, even though he passed away in 2007. But today is the 100th anniversary of the birth of Francis Albert Sinatra (who died in 1998).

Given that Dad lived, breathed and crooned Mr S, no doubt any consideration I might make of the Voice (or latterly, the Chairman) will bear the traces of what I made of my father. But one titan at a time, please.

My brother and I have been playing Sinatra songs for a few months now, both live and recorded, on our own and with our superb band. (Even if I say so myself: Frank always did. No-one venerated the talents of musicians more.)

We have tip-toed into his canon at various points over the last 30 years. But you don’t realise the artistry involved in a Sinatra classic until you try to make a decent fist of performing it.

For the band, it’s the extraordinary sure-footedness of the swing of his music. Forty to 50 musicians in a studio, strings and horns and keys and snares, effortlessly landing “on the one”, all at the same time.

Hard enough for us seven to do it. To even get close is to feel an incredible propulsion – the beat and groove of sexual desire itself.

For the singer ... whew. It’s tough. I’ve been trying to excuse my limitations by saying what is, in fact, completely true: as for singing in the style of Frank, I had no choice in the matter.

My father used to croon this restive child to sleep by singing Sinatra ballads straight onto my temple – officially the thinnest part of the human skull. Had it been Elvis, McCartney/Lennon, Bob Dylan, my duties in the last six months would have been entirely different. However, literally and neurologically, I am wired to be Frank.

But to dip down directly into the glittering, dark-moving river of The Voice? It is chastening, intimidating and (at the very least) proves that every day’s a school-day. I could type off the end of these pages about it.

The technical stuff is easily stated. At his artistic peak, Sinatra joins together words and melody in enormous, long legatos – the Italian bel-canto tradition, mixed in with the diaphragm power of jazz instrumentalists.

But those words aren’t distorted and mangled the way opera singers do, turned into mere vehicles for virtuosity. Sinatra drops them into his vocal stream perfectly and clearly, his diction sounding like Americans talking in their streets but in an elegant and self-possessed way.

All these resources were used to get to the heart of the early-to-middle-20th-century American songbook that he chose to sing, for most of his career. We’ve been doing his version of Rodgers and Hart’s I Wish I Were In Love Again. Among many gems is this line: “When love congeals, it soon reveals/The faint aroma of performing seals/The double-crossing of a pair of heels/I wish I were in love again.”

On its own, maybe a lyric too clever for its own good. But slathered across the toasted bagels of Sinatra and his band, it becomes the finest survivors’ wit, delivered from the heart of the mid-fifties battle of the sexes. If one is to be a straight male, something like this is what it will always feel like.

Speaking of masculinity, that brings me the other experience of the last few months, which is finishing the second volume of American journalist James Kaplan’s massive biography of Sinatra, this one titled The Chairman.

Kaplan and his publishers have chosen the cover image very well. For a publicity photograph taken in the mid-fifties, it’s a remarkably aggressive and challenging expression. Sinatra looks over to the side, as if he’s just heard or seen someone who displeased him and is about to let them know. He is angled, handsome, self-consciously powerful.

It would be accurate to say I have devoured both of these books. Kaplan seems to leave no significant moment in Sinatra’s life unrecorded, in a style that combines literary flourishes, hard reporting and wise-guy street-smarts (and for me, works brilliantly).

But the character he reveals ... it is staggering how much Sinatra lived at the absolute extremes of existence. In the morning he’d shout at his black valet for ill-pressed trousers, then make calls on behalf of progressive Democratic candidates.

In the afternoon he’d disappear for a while with some starlet fallen off the conveyor belt, then bring them giggling into the orbit of some of America’s most loathsome gangsters.

In the evening he would saunter into a cavernous recording studio and meticulously record a work of genius – then quit after the final take to fly his private jet to Vegas, oiled with Jack Daniels and imperialising his entourage till the dawn broke. Rinse and repeat for four decades, with only minor variations, until time caught up with him in the late seventies and early eighties.

You keep asking all the way through Kaplan’s narrative: all this mad alternation between chaos and control in his lifestyle – is this what Sinatra needed to make those thunderous swing tracks, those vast penitential ballads? The former his silverback roar, the latter his lowing for forgiveness?

In any case, it’s a happy realisation: I didn’t go there, and I never will. It’s not that I don’t recognise the nature of the furies. “Sinatra craved class like a junkie craves the needle,” said George Jacobs, his ever-observant valet.

So many popular musicians I’ve met in my life are trying to build cathedrals of sound, while being perfectly aware of the shacks and ruins that lie behind them and which they can’t quite obscure. Music as therapy that you get paid for, rather than pay for: Sinatra exemplifies that.

But another quote from the book makes it clearer: “There isn’t any ‘real’ Sinatra. There’s only what you see. You might as well try to analyse electricity. It is what it does. There’s nothing inside him. He puts out so terrifically that nothing can accumulate inside”.

This is on the harsh side – his lifelong torch for Ava Gardner is a clear disproof – but captures something true about Frank Sinatra’s life and achievements.

He was defined early by the search for stardom – that total confirmation of the performing self – and let that electricity spark through every aspect of his life. As Kaplan’s biography have it, this made Sinatra “both loved. And feared.”

Reeling from his full story, I’m happy just to aim for the former.

Yet that Sinatra was driven by an energy, rather than an intent, seems pretty clear too. There is a beautiful memory that Kaplan unearths from his early years. Sinatra tells his schoolfriends he often lies on his bed, lost in silent reverie, “listening to the music of the spheres”.

“Yeah, yeah, paisan,” you can imagine his Hoboken friends saying, “now let’s play ball.” But any committed musician knows exactly what he’s hearing. The question is: how much life and how many people do you scrunch up in order to make that impossible music real?

It’s been a ring-a-ding ride, but I’m glad to put Mr S to rest for a little while now. To rework the famous old phrase: It’s not Sinatra’s world, anymore. And I want to live, richly and affectionately, in mine.

Both Sinatra: The Chairman by James Kaplan (Doubleday) and Hue And Cry’s Sinatra tribute album, September Songs (Blairhill), are out now.