This seems to be Jones’ beat – he’s previously written a bestselling biography of Jim Henson. So he’s staked out the role of Boswell to pop entertainment moguls. And given the size and fervency of the following for Lucas’ products, there’s obviously an audience for it.

In many ways, there is simply not all that much to the story. Lucas made one art-house film, THX 1138, that failed commercially. He moved on to a hit with American Graffiti. This allowed him to make Star Wars – and that’s fundamentally the end of the story. The rest is just the minding – for better and worse – of that monster franchise.

There’s actually a lot of fun in Jones’ retelling of Lucas’ early years – of growing up in California, of film school at USC and of the early days among legendary film figures to be. The tales of Lucas with his “big brother” Francis Ford Coppola and his “little brother” Steven Spielberg – among others – in their early days feels like a prequel film itself.

Film geeks will rejoice at the detailed explanation of how Star Wars was made. And there’s great insight into the way the film industry works – and how Lucas and company changed it.

Jones walks us through the myriad influences that inspired Lucas’ interests: the comic books, the old-time serial adventures such as Buck Rogers and Flash Gordon, Edgar Rice Burroughs and other pulpy adventure tales, in addition to art filmmakers such as Federico Fellini, Francois Truffaut and Akira Kurosawa.

We’re supposed to see this as a sort of portrait of the artist as a young man. But here lies the rub: the portrait is, ultimately, of an entrepreneur and tycoon since, after Star Wars, anything one might call “art” ends. The remainder of the story is simply riding the Star Wars train.

And, while Lucas was also an innovator in other aspects of the modern movie game – technology, merchandising, sequels – the unavoidable fact remains that he made a few good movies four decades ago and a huge amount of dross since.

Director Peter Jackson describes Lucas as “the Thomas Edison of the modern film industry”. Jones credits him with having “an inherent ability to hire the right people, and a preternatural knack for asking the right questions”. But this makes him, more than anything, the Steve Jobs of the film industry. He isn’t the guy who actually did the inventing but the one whose vision – and insistence on seeing it realised – drove others to make it happen.

That’s not nothing. But the second half of the book – focusing on things such as Lucas’ Industrial Light and Magic visual effects company, as well as lesser business details – is like going from the romance and excitement of Star Wars to the legalistic trade and diplomatic themes of the second trilogy.

Lucas emerges as a likeable and largely admirable person – a tremendously accomplished guy who’s enjoying his life and has done good things with it. But, again, is that a story worth telling – much less reading and paying for?

Rogue One: A Star Wars Story is now upon us and, as The New York Times critic A.O. Scott put it, reviewing Attack of the Clones in 2002, “Like weary Brezhnev-era Muscovites, the American movie-going public will line up out of habit and compulsion ruefully hoping that this episode will at least be a little better than the last one”.

Many people will keep lining up with them. Better to lose a few bucks on those new hopes than on a lengthy and intermittently interesting tale of the guy who disappointed them for so terribly long.