‘You don’t know who I am. You don’t know where I am. And you’ll never see me coming.”

Ben Kingsley, actor, Knight of the Realm and now Marvel Super Villain, is so keen on his new catchphrase, he's in danger of wearing it out.

Kingsley, who is 69, is looking youthfully svelte in a purple sweater, and there's a boyish glee about the way he recites the line and discusses his role as The Mandarin, a new arch-nemesis for Iron Man 3 's Tony Stark.

Never mind the Academy Award for Best Actor, his 1984 Grammy win, his one-time role on Coronation Street , his star on the Hollywood Walk of Fame or his various trips to Buckingham Palace; right now, for the first time in his career, Sir Ben Kingsley is an action figure with his own nefarious shibboleth.

“That was my favourite line and that steered me through the film,” he says. “Underneath that – when you’re playing what people categorise as the baddie or the evil one – you have to remember that the bringer of evil has their own sense of righteousness. They profoundly believe that what they’re saying and doing is for the good of civilisation.”

What is it with Hollywood and British baddies? Even when they’re not using their own accents they still often hail from the land adopted by Benedict Arnold.

“Ah. Because they turn up on time. Because they’re polite. And they know their lines.”

The Mandarin represents a curious mash up of Osama bin Laden and Lord Haw-Haw. An international terrorist with a penchant for political broadcasting, his voice – think John Huston at his most patrician – is pointedly occidental.

“I do have a very good memory for voices,” nods Kingsley. “So I can pick from a whole mosaic and put them together to make that creature on the screen.

Robert's character, Tony Stark, does say to Don Cheadle: "He sounds like a Midwest preacher", and I thought: "Well, there's your clue". And I thought about all those wonderful voices I've heard that use rhythmic speech and repetition and that patriarchal sense of righteousness. Because what would really disturb a western audience is that the bad guy sounds presidential, that he's a voice of western authority."

So it’s not a precise Huston imitation?

“Not consciously. I was yodelling in the bathroom one day and out it popped. It’s a bit like cooking. It all goes in a pot and something else comes out.”

Today, as the Iron Man 3 road show rolls into London town, various representatives of Marvel and Disney couldn't be on higher alert if Kingsley was, in fact, an international terrorist. Having achieved the hitherto unthinkable by stealing the movie from under Robert Downey Jr's nose, the English actor is surrounded by various apparatchiks as he walks into a London hotel suite to meet me. This is the Marvelverse: there are plot twists and reveals to be protected. The talent must be minded at every turn. Gwyneth Paltrow – Kingsley's taller-than-you-imagine co-star – swans past the door with a veritable army of assistants.

“They are very welcoming,” insists the star. “They make a new boy like me feel really, really at home. Within seconds on set we were rolling up our sleeves and mucking in and getting on with it. Everybody involved is so confident, so assured. They can afford to be welcoming. It makes life a lot easier.”

He had not been familiar with the franchise beforehand; he has never been a comic book guy. The experience of shooting Iron Man 3 , however, has converted Kingsley to the way of the fan-boy.

"So I caught up with the franchise," says Kingsley: no, contrary to tabloid legend, you don't have to call him 'Sir'. "And I loved Iron Man 1 and 2 and The Avengers . Loved them! They have a real tenderness and affection in them. They're not cynical, but they're not sentimental. They're so witty and ironic. And yet there's so much self doubt in the Marvel world. It's very human and very attractive for me. I've been missing out."

So he never worried that a comic book villain might be a little stifling for an actor of his calibre?

“Oh no. I love parameters. When you watch Wimbledon there’s white lines and umpires and within those beautiful limits the competitors do battle and the spectators have an amazing time. When you read a Shakespearean sonnet, it’s 14 lines. I loved that a lot of my character is very highly scripted in the form of political broadcasts. I don’t need to improvise. If you move outside a certain space you’re just enjoying yourself without necessarily communicating anything to the audience.”

Ben Kingsley was born Krishna Bhanji in Scarborough and brought up in Salford. His father, Rahimtulla Harji Banjhi, was a doctor of Gujurati descent; his mother, Anna Lyna Mary, was an English model and actress.

Even as a youngster he was known as “the Danny Kaye of the family” and he continues to think of himself as a “song and dance man, a story teller”.

His parents were distant and unsupportive of the youngster’s burgeoning ambitions; the Danny Kaye comparison was not entirely complementary.

Still, the young Ben Kingsley – to use his adopted, Anglicised name – soon found an alternative family under Trevor Nunn at the Royal Shakespeare Company. Aged 23, Kingsley turned down an offer from producer and manager Dick James – of Elton John and The Beatles fame – to make him into a pop star, so that he might instead devote himself to study and performance of The Bard.

“I never went to drama school,” he recalls. “So that became school and family. To this day I think I’m a language-based or driven actor because of my time there. For any actor playing any character there’s always a trigger and I think with me it’s probably the voice. After that other things fall into place.”

His first screen appearances in Coronation Street and Crown Court made Kingsley a household name in three-channel Britain long before his 1982 Oscar win. Having subsequently worked with Martin Scorsese (on Shutter Island and Hugo ), Steven Spielberg (on Schindler's List and AI ) and Roman Polanski ( Death and the Maiden and Oliver Twist ), Kingsley still speaks of these early roles with tremendous affection.

"I got promoted to QC in Crown Court having won all my cases," he notes proudly. "It was wonderful."

We’re not surprised by the little boast: Kingsley famously can recall almost every line of every script he’s ever worked on.

“I want to learn the entire script before I arrive on the set if that’s humanly possible,” he nods. “Sometimes it’s not. But a well-written script is like a symphony.

“And you don’t always shoot in sequence so you have to understand the symphonic arc. I like to be very well acquainted if not word perfect with the whole script. All the directors that I have treasured working with have a sense of the rhythm of the human pulse. I never really developed a technique. But I do love learning my lines.”

Having worked in show-business for almost 50 years, Kingsley is currently looking forward to one of his busiest and most high-profile seasons. Later this year, we'll see the actor in A Common Man and in director Gavin Hood's keenly anticipated adaptation of Orson Scott Card's Ender's Game .

When did he become so, well, sci-fi?

"Only in the last few years," he says. "Partly because there's been an evolution in sci-fi movies. They're now far more psychologically sound, more linked to technologies and possible futures. I wouldn't have been appropriate for the genre before. A classically trained actor wouldn't have made sense. There were no layers of humanity or mythology there before. It's evolving into something quite extraordinary. Kenneth Branagh's Thor is a marvellous franchise. It's so layered and – dare I say it - so rooted in Shakespeare."

Does it matter that Iron Man 3 and Ender's Game are likely to be two of the year's biggest box office hits? Kingsley has championed smaller projects and interesting directors throughout his career. The past decade has seen him take on such indie, underground pieces as Fifty Dead Men Walking and The Wackness , in which he locked lips with an Olsen twin.

“Box office does enter my mind now because box office measures the number of people who have seen it,” says Kingsley.

“And if I’m really happy with the work I want a lot of people to see it. Also when I’m wearing my other hat as a producer I can’t afford to be blasé about box office. I need to understand the science of the figures and science of getting something out there. It’s a very important part of the process. It’s an extraordinary business. You enter into it fully or not at all.”

Away from RDJ and the Iron Man hoopla, Kingsley spends most of his time in Spelsbury, a sleepy Cotswolds village, with Brazilian actress Daniela Lavender, his wife since 2007.

“I’ve always tried to lead a balanced life so that when I’m not on – either now in front of you or in front of a camera – then I’m probably cooking for my wife. She’s an actor as well. And we do struggle with being separated due to career demands.

"But when we are together it's all the domestic, simple, nourishing things of life that I love. I love the English countryside. I love my garden. I love fabrics and painting. I love fixing things and oiling things. And from there I'm ready to take a running jump at anything."

yyy Iron Man 3 opens today and is reviewed on page 11