Every few years there is a rumble in the Hollywood jungle, a King Kong-style parting of the branches followed by the emergence of one of the biggest beasts in film – Ridley Scott, or Sir Ridley as this South Shields lad prefers not to be called.

Next week, the director returns with Prometheus, a prequel to his landmark 1979 film, Alien. For dedicated followers of science fiction in film, this is the nearest thing to finding the God particle. Even for those who are grown up with sex lives and mortgages, Prometheus is a genuine film event, like a new Scorsese in a sea of Pirates Of The Caribbeans.

Time, then, to venture again to the court of the great Scott. Judging by his past encounters with (male) interviewers, the drill is to generally bask in the glow of the man who made Alien and Blade Runner, the alpha and omega of cinematic science fiction, and lob in a few questions about Russell Crowe, his favourite leading man of recent years.

This time it will be different. This time the starting point is a line from Prometheus itself: "Big things have small beginnings." The big stuff about 74-year-old Scott is well known – Alien, Blade Runner, Someone To Watch Over Me, Thelma & Louise, Black Hawk Down, Kingdom Of Heaven, the five Oscars-winning Gladiator and the rest of his 20-plus films – but the small beginnings are a relatively distant planet.

Out there lies a tale of a strong mother, a peripatetic childhood, and a little boy who was swept out to sea only to be rescued by the very thing that could have destroyed him. If Scott ever films this, it will be a hell of a tale.

First, though, Prometheus. Hundreds of journalists came from all over Europe to London last month to watch 12 minutes of footage. A whole 12 minutes, yes. The action opened on Skye (Scott flew in Apocalypse Now-style in a helicopter for one day) and progressed to snapshots of life aboard the space ship Prometheus. After the screening, the internet buzz duly moved from defcon three to two. If they gave Oscars for hype, and it can only be a matter of time, the Academy Award would go to Prometheus.

Scott had been asked many times to revisit Alien territory but resisted the lure. "I thought the franchise was used up," he says in tones still more Tyne and Wear than Beverly Hills. "You can't do the good old beast again. He's just no longer frightening."

Yet something had stayed with Scott since Alien, and that was the sight of a giant fossilised being that fans of the film came to dub "the space jockey". The space jockey, his chest caved in, appeared to be the pilot of a downed spacecraft. Wondering who he was, how he got there, and what his mission had been, Scott had his starting point for Prometheus.

Was there another reason Scott, at this point in his life, felt the need to return to Alien territory? He made the first film, only to see his baby handed to James Cameron (Aliens) and David Fincher (Alien 3), then on to yet more directors. Is there a sense of unfinished business?

"No. I'm very competitive but I don't care." What about any rivalry with Cameron? If Scott is King Kong among Hollywood directors, the Titanic helmer would have to be T. rex with SAS training. Didn't it bother him that Cameron took it on? "Oh no, no, no. Actually, Jim and I are quite good friends. Jim did number two because he came in with the story. I'd honestly forgotten about it. I wasn't even thinking about doing an Alien 2." Still, the first he knew about a sequel was when he read it was happening.

If someone was to finish the tale, surely it would have to be him. "I don't really know," he says in comic fashion out of the side of his mouth. "I don't care." Really? "If this [Prometheus] justifies doing something else I would certainly do it, because I've got some very specific thoughts on what to do." In short, then, he cares, even if it does have to be dragged out of him.

No wonder he cares. Alien holds a special place in the Scott history. Incredibly, it was only his second film after 1977's The Duellists, a Napoleonic War drama adapted from the Joseph Conrad short story, The Duel. The two films represent both sides of Scott's personality and work. The Duellists, starring Harvey Keitel and Albert Finney, is cerebral fare that won him the best first film prize at Cannes and had the New York Times thrilling over its "almost indescribable beauty". The other is sheer high-octane entertainment with a strong woman – Sigourney Weaver's Ripley – in the lead. Thinker or showman, artist or entertainer, admirer of heroes or worshipper of heroines, auteur or blockbuster director, Scott shifts between these various points.

He rather fancies the label of auteur, a director whose work, like that of Hitchcock, Godard or Loach, is so distinctively his, in themes and style, that he is clearly the author of it. Yet, as emerges when I ask if he feels the weight of fan expectation over Prometheus, there's a certain reluctance to call himself one. It is as if he's the two Likely Lads rolled into one – one part Bob, fiercely proud of his achievements, the other part Terry, calling out "Away, man" at any whiff of pomposity.

It matters that people like Prometheus, he says, but what concerns him most is whether he's pleased with the result. "I've always had that view. If you're a bit of an auteur – pretentious word, auteur, which I guess I am; I've done enough originals now to be called that – by being that, you have a very clear view about what you've just done, however it performs. If it does well, that's terrific. Like Gladiator. I knew what I'd done, I didn't know if it would do well or not, but it did."

Since Prometheus concerns itself with the origins of mankind, I ask if he is religious. "Religious in the context am I good, am I bad, am I medium?" Religious as in believing in God. "I believe we were created. I don't think we are just a biological accident."

We kick the subject around a little more, eventually coming to Jesus, as you do. "Was he crucified? Certainly. Did that happen? Certainly. Was he the son of God or was he just a great fundamentalist who had lots of good stuff to say and therefore bring some kind of order and control to what seemed to be an out of control world?" The end result of all these questions? "I believe up to a point. It's intuition."

On to more temporal matters, like how a South Shields boy comes to earn millions and be sitting in a five-star hotel today.

A striking fact of Scott's career is its sheer longevity. From his Hovis advert (voted the public's all-time favourite) to Prometheus, it has lasted almost 40 years. You don't stay that long at the top of advertising and movies without being tough.

Emboldened by his experiences in advertising, Scott made The Duellists, not knowing it was deemed such a rarefied beast it was only shown in seven cinemas. Still, the film made it to Cannes, where he won the newcomer prize. In the middle of his Cannes story I cut in to clarify something and am treated to the Scott glare. Like James Cameron or a High Court judge, Scott is not a director to suffer interruptions gladly. His on-set battles during the making of Blade Runner, particularly with Harrison Ford, are legendary. You can see why he became pals with Russell Crowe. Their nights out must be like Vesuvius and Mount Etna getting together over a nice claret.

He glares, I ask anyway, and on we plough. Scott is plainly a man who enjoys a scrap. Has he had to battle? "Totally!" he shouts gleefully. That's Scott. A resilient sort, but more importantly a smart one. In a business that's all about business, he's a player.

"After 30 years I'm a pretty good lawyer, I'm a bloody good agent and I've learned the business inside out. I've learned to surf with the fors and againsts. There is a lot of againsts in the business, mainly because now it's so expensive to do anything. Prometheus, as other big films go this year, is probably one of the smallest in budget, mainly because I know what I'm doing. I kept a rein on everything because I'm also a producer."

His production company, RSA, founded with brother Tony in the sixties, operates in the UK, US and Asia, making feature films, animation, advertisements, music videos and television programmes. As a producer alone, Scott has fingers in pies from TV's The Good Wife to the post-tsunami documentary Japan In A Day. His three children from two marriages are writers and directors. Film has been good to Scott, and while not every movie he has made has been a winner – not that he thinks so, as we shall see – few could deny he has worked for the success he's had.

Big things, small beginnings. Scott was born in South Shields in November 1937. His father, Frank, was in the army, so the family moved around a lot. Even when in one place it was clear to the Scott boys – Frank, the eldest, Ridley and Tony – that with their father away, their mother was in charge. From the start, the lad who would grow up to make heroines out of Ripley and Thelma & Louise had his own strong female role model, his mother Elizabeth Jean Scott.

"My dad was the gentleman. A gentle man. A sweetheart. My mum was the tough guy. I think my mum should have been in business," he says, laughing. It was his mother who kept them in line "with the strap and the cane". Is he more his mother's son or his father's? "My elder brother was more my dad's son, and Tony is a little bit of each. Tony's a bit more forgiving than I am."

An army family, then, headed by a strong woman. The kind of childhood that breeds a certain robustness in a boy, makes him an organiser, a doer. He wasn't that confident at art school, he says, despite getting in "everywhere" and eventually going to the Royal College of Art in London. He obtained first-class honours and a travelling scholarship to New York. Soon he was living in the YMCA, no money, no contacts. At that point, the young Scott had two choices: fight for a break or take a flight home.

"I landed in New York not knowing anybody and that was really the beginning of having to pick up a phone, put in 10 cents, say hi and get myself a job." After a stint in documentaries it was home to the BBC as first a set designer then a director. "All the time I was evolving," he recalls. "I was always a good organiser. Very neat, tidy, orderly – almost military in that respect. It helped me doing my job."

The jigsaw has all its corners, but I'm wondering about the pieces in the middle, the bits that explain how he so confidently took on America. He didn't make his first film till he was 39. So what made him, America or South Shields?

"Everything makes you," he replies. "My whole upbringing – I went to 10 schools so I was pretty confused. It's all very well saying, 'Don't worry, he'll pick up moving from Llandaff Cathedral to Ealing, no problem.' I didn't know where the hell I was."

But he had his brother Tony, seven years younger than him, and he had a sense of adventure. The happiest period in his childhood was when he lived in Whitley Bay, a mile from St Mary's lighthouse near Blyth. In those days, he says, parents would just turn you loose with a bag of sandwiches and a Thermos.

"We'd go off in the goddamn wilderness. I'd be, Christ, I'd be seven. Seven! There were no weirdos in those days to molest you, or at least I never came across any." His mother didn't know half the dangers they got into, including, in his case, being swept off the pier and out to sea. Somebody up there liked him enough to sweep him back in again. "That was a miracle." When he got home his clothes had shrunk from the seawater. Mum, none the wiser, remarked that he was growing quickly.

At a Q&A following the Prometheus footage, Scott asked the audience to stop calling him Sir Ridley. "Bloody embarrassing." He received the knighthood in 2003 and said afterwards: "As a boy growing up in South Shields, I could never have imagined I would receive such a special recognition." Today, he's honoured, "of course", but he's still "a little uncomfortable" when he hears the words.

It's not that he thinks Britain is a hopelessly class-bound, fuddy-duddy old place. He still has a home here (plus places in France and Los Angeles). Despite his wealth, he thinks of himself as classless. His father, even though he ended the Second World War an acting brigadier general, was working class.

His father and his uncle were destined for the mines until their mother, Scott's grandmother, stepped in and they became shipping clerks in Newcastle instead. My sons are not going down the mine, she said. Another strong Scott woman.

We're coming to the end of our allotted time. He's looking fairly rosy-cheeked, which might be the result of a warming trip down memory lane. Any regrets at this point in his career? "No."

Not even Legend, with its elves and pixies? Not GI Jane, or A Good Year, the wine-themed romantic comedy with Crowe that had critics reaching for the hard stuff? I'm paraphrasing – what I actually ask him is "None at all?"

"I haven't regretted any thing, any film." All he's ever worried about, he says, is following his intuition, his belief that things will turn out OK. That, if anything, is his religion. The sea that swept him out has carried him home, from waves to shore, from Alien to Prometheus. Big things have small beginnings. n

Prometheus (15) opens on June 1.