Daily Info catches up with cinema's biggest giant Steven Spielberg – whose BFG strides onto screens this week. From the digital revolution to the importance of watching black and white movies, the directorial colossus talks intuition, influences...and imagination.

How did you first encounter Roald Dahl's book, The BFG?

I read it to my kids. I was more familiar with Charlie and the Chocolate Factory. But it had a great illustration of the characters - a little girl and a giant with huge ears. So I picked it up in a bookstore and read it out loud to my kids. I didn't see it as a film back then – only a way to popularise myself with my family.

What made Ruby Barnhill (Sophie) and Mark Rylance (the BFG) right for their roles?

Luckily I'm not an actor, and because I'm not, I don't come from a part thinking I can play it. I'm reliant on the people I cast and I'm as much in the actors' hands when I'm directing as they feel they're in mine.

It's very hard to deconstruct the intuitive tickle I get when I see someone after looking at hundreds of hopefuls and I dare to imagine I might have found her. You can't deconstruct that and say "here's why". I met Mark in the 80s when I was casting Empire of the Sun; I've seen him on stage. He's a liquid actor who can fill any shaped vessel and can do practically anything. But the moment I felt he would be right for BFG was on the first day of shooting Bridge of Spies. I just had an intuition there'd be no one better. He thought I was just asking his opinion on the script!

As a director, can you simply watch a film like an audience does?

I've been able to get into the habit, since I was first starting out, of suspending my disbelief like every other audience member and forgetting everything I know about how a film is made and how I make them, and to let a film that someone else has made just wash over me. A lot of people say, 'Don't you think about where they've put the camera or how it's lit?', and I swear I don't. Even if it's not a very good movie, I don't fall back and try and figure out how the film was made. I just let the film have its way with me.

After such a great career, what would you say has been the secret of your success?

I'm just proud I've been able to stay interested in making movies all these years and I'm really happy I get to keep working. I've met a lot of my heroes. I met Frank Capra after he saw ET and liked it. I took him to lunch. I've met David Lean and Kurosowa. And I've seen the one thing that happens when directors get older: they still have the passion and the determination to tell stories but because of their age, the people who do the hiring look at you as a relic from the past. And one of the reasons I developed Dreamworks back in 1994 is I said I'm not going to be one of the relics from the past. And if I have to hire myself, and form a studio to do it, by God that's exactly what I'm going to do!

So you're not going to rest on your laurels anytime soon?

I'm in my 70^th year I guess. I don't get tired. I should but I don't. I'm telling stories, making movies with great actors. I don't look at myself with the word legacy because I'm so busy now and looking ahead. I do get the chance to look back sometimes when I'm being interviewed and talk about movies. but don't do it often. I know the movies I've made and the impact they've had on people because I talk to strangers every day all round the world. But I tend to think if I dwell too much on that it's going to make me sit back on my tush, and I'm not ready to do that.

What, for you, is the essence of being a good director?

I can only speak for myself. I'm a conservative director. I have a lot of ambition about my predecessors - all the geniuses we're learning from whether we know it or not and on whose shoulders we stand. I do a lot of looking back, understanding what makes a good story. Starting with silent movies where the visual arts were explosive, very direct and led you to an emotional reaction, and huge climactic endings, without any words at all. And how when films first found their voice they all sounded like plays. Until Howard Hawks decided they could talk faster and threw a couple of fantastic reveals into his composition. My whole love of the medium comes from paying attention to the past. And respecting all the movies that have been made over the years.

And that's what I say to film students: you need to look at the old movies. You know, I used to have to pay my kids $10 to watch a black and white movie. I said if you watch Red River with me, I'll give you $10. Twenty minutes later they gave me my $10 back!

What do you think has been the biggest change in the way films are made over time?

The biggest change is that before the digital revolution, you needed to use your imagination to be able to craft an illusion that the audience would accept as real. Even a movie like the original War of the Worlds where you can see all of the wires on the flying machines. The audiences then were able to see the wires but not include them to spoil the illusion. They forgot the wires. Today, with the digital revolution, you can literally put anything on the screen, whereas it took a lot of imagination to figure out how to craft an illusion. So illusion is gone; we no longer have to use practical magic to make you believe something's real because through digital effects it's real, it's photo-real. And there're pluses and minuses to that.

So what does that mean for The BFG?

For me, the success of BFG is measured not just by the amount of heart that's expressed by these two characters. But also that twenty minutes into the movie you'll hopefully forget there are any effects at all. If a movie's working, you forget there are any effects.

The BFG strides into cinemas, directed by dream-worker Steven Spielberg. But the BFG belongs to Mark Rylance whose lilting West Country tones beautifully articulate Roald Dahl's nonsense language - creating, as he does so, an indelibly engaging character that lifts the film to its heights.

Spielberg lives to tell stories. Truth is, though, there's not much storytelling in The BFG. Sophie lives in an orphanage, self-reliantly running the place, spending her nights with little sleep, wakefully walking the corridors. Berating some "bladdered" blokes coming out a pub, Sophie sees what she shouldn't - the giant hand of the BFG as he stalks the nocturnal streets of London. A hand that reaches to snatch her from the bedroom in a scene slithering with John Williams' scary score.

Bounding away to Giant Land, the BFG tells Sophie that, as she's seen him, she's with him forever now. Fearing to be eaten, Sophie soon realises the Big Friendly Giant is no chiddler guzzler – happier swilling his yucky, veggie snozzcumbers. But the neighbourhood giants know a human bean when they smell one and they'll stop at nothing for a scrumdiddlyumptious Sophie-snack. What to do?

Whereas Tintin saw Spielberg in full-on Raiders of the Lost Ark mode, brimming with action and adventure, the BFG is more E.T. and Close Encounters, a film of relationships and communication. Sounds dull but here's where Mark Rylance (Bridge of Spies; Wolf Hall) scores big-time. Blow Roald Dahl's gloriumptious, gobblefunk language and the BFG is sunk. A few set-pieces aside, the film relies on the sparky chemistry of Sophie (newcomer Ruby Barnhill) and the BFG. So much so that the most inventive action takes place in the BFG's own cave-home as the tiny Sophie gets accustomed to his world or escapes the clutches of the bigger, badder giants.

But years of Shakespearean dialogue have not been in vain and Rylance relishes every Dahlian syllable. The clarity of delivery, rarely heard in cinema these days, even with ordinary speech, is alive with characterful inflection. Spending time with the BFG is what the story's about and – like Sophie – we warm to his peaceable, muddle-mouthed ways. And Ruby Barnhill's feisty heroine is refreshingly direct and blub-free - no crying or tantrums, just attitude and a rather nifty idea for ridding Giant Land of the bully-boys.

Being Spielberg though, there are flashes of invention and catch-fire visuals that remind you of his mastery. The BFG deftly forming into a lamp-post, truck and statue as he hides from passers-by in London; the intricate, Heath-Robinson contraptions, contrived from bits of our world, furnishing the giant's home; the luminescent world where the BFG catches the dreams he'll blow through a magical trumpet into the minds of sleeping people.

And then of course the fart jokes. Because that's what happens when you drink frobscottle – a wee-looking liquid where the bubbles go downward, with inevitable results. Who'd have thought Spielberg's artistry and sense of timing would extend even to this? Yet it's so – a fine double-take-look-to-camera is perhaps the funniest moment in the film.

A Buckingham Palace sequence shines and Penelope Wilton (Downton Abbey) is fabulous as "Her Majester" Queen Elizabeth II. And yet - maybe we Brits are over-familiar with it - the bonging of Big Ben as the camera pans across the Houses of Parliament, and the pomp of Rule Britannia as the Palace comes into view, is easy-referencing. It jars. Even Paddington didn't do that.

Happily, the brightly funny Gulliver-esque happenings at the Palace are an inventive compensation. Although I'm sure Debretts would have something to say about the staff calling the Queen ma'am to rhyme with smarm, and not with jam.

Less fast and furious, more fun and friendly, The BFG makes a mark that stays with you, as a good friendship should. Short on stuff for smaller-kids, there's certainly more for middling 'uns and adults.

Definitely not a whizzpopper, then. And you'll have to read the book - or see the film – to know what that means. Or drink some frobscottle.