“The whole cosmos centres around me,” Robert Downey Jr joked earlier tonight. In reality, a joke like this couldn’t be closer to the truth. In many ways the cosmos does centre around him. Queues to see the Hollywood actor speak at the Cambridge Union stretched beyond the street, and the multitudes that couldn’t squeeze into the Chamber were delighted to crowd before projectors in rooms elsewhere in the building. All this, in the hope of seeing a man in the flesh, a man in the flesh talk.

Though, maybe, this is not just any man. In July, Robert Downey Jr topped the Forbes list of the highest paid Hollywood actors, with a predicted income of $75 million this year alone. To put this into perspective Leonardo ‘The Wolf of Wall Street/Everybody’s Favourite Actor’ DiCaprio earned a mere $39 million.

Downey Jr is in the UK at the moment promoting his new film, The Judge. But when he came to speak at the Union he felt no urgency in promoting it to us. Instead he was keen to point out his favourite college crest (Lucy Cavendish...), slouch in his chair, legs over the arms, like he was being “sucked through the rabbit’s hole”, as he put it, and answer questions about how cool it was to know Scarlett Johansson.

I had arrived at five, an hour early, to interview this Hollywood giant, skipping the afternoon-long queues in the process – though no less schoolgirl-jittery with excitement. I had spent the last day compiling questions that would make a change from the “same non-questions” with which Downey Jr says he is all too familiar. Yes, by five I was ready to take him head on with questions from drug abuse to the genre that’s reinvented his career.

As I was ushered into a pressroom at the Union with other representatives of the Cambridge media, we were told by a slickly dressed, brown-brogue wearing Warner Bros. ‘Publicity Manager’ that we could only ask Mr. Downey Jr one question each. What. That’s right, only one question each. It seemed as if I too had been duped, drawn into the zealous parade of people that bring out the party-poppers whenever a celebrity shows up. Students who had achieved the oh-so-rare accolade of liking the Union’s Facebook status fast enough were invited to have a picture taken with this God Amongst Men. Professional photographers were there with the whole shebang: a tiny camera with a lens bigger then my head and a pair of fifty million watt light bulbs to shine out any blemishes on the students’ pimple-ridden faces. A Hollywood keepsake for life, I’m sure.

When he finally made it over the room to us, minutes later (with his publicist keen to remind him of the time), he pulled over his seat and moved it forward saying, “let’s try this too close for comfort.” It was only at this unique distance from him that I really had an opportunity to look at him, the way he was chewing gum, like James Dean does a toothpick. He wore a smart, brown jacket and tie, but kept it Hollywood-casual with a pair of jeans, loosening his top button, his tie low beneath his collar. Oh, and his shoes. His shoes were great. Indigo High Tops, I would describe them. With platforms that Tom Cruise would be proud of. This was Robert Downey Jr close-up, but not personal. It was the very same Robert Downey Jr we see from the distance of our home screens whilst he stands in front of a camera lens on the red carpet during another Iron Man première. With a little more moustache, it would be the very same Robert Downey Jr we see as Tony Stark in every Marvel movie.

When it was my turn to ask him a question, I took my time. I began by mentioning how he had topped the list of Forbes Hollywood pay list, beating the likes of Bradley Cooper, and even Leonardo ‘Fifth-Time-Oscar-Snubbed’ DiCaprio. I ask him, what, then makes you different from these guys? Why do people go and see a ‘Robert Downey Jr.’ movie? And his answer was more truthful than I could have imagined.

It wasn’t because he offered something radically different to any of the other actors on the Forbes list, that he was God’s Gift To Earth, and now walking among us. But simply because, as he said, “it’s like you come to trust certain brands, you know.” “Nowadays, in the digital age, you begin to associate those brands with what you hope them to do.” In fact he couldn’t be more right. As the writer Ben Walters said, and was quoted in The Observer a few years ago for saying, “The whole point of Iron Man is to spend a couple hours in Robert Downey Jr’s company – and everyone’s happy with that.”

The ‘brand’ of Robert Downey Jr is Robert Downey Jr. The Robert Downey Jr of Iron Man, the Robert Downey Jr of 2008, the year he took back Hollywood. The Robert Downey Jr of on and off the screen, the Jr the public hate to love and love to hate. He once described himself as “this ne’er-do-well embittered, unemployable guy arguing with some hooker outside a Malibu hotel scrambling for a syringe.” He was the outsider, three narcotics-arrests too many outside the ‘inside’ of the Hollywood Industry.

But this poster boy of pharmaceutical mismanagement, as he once called himself, has scrambled back. With the help of Mel Gibson, who backed him when no one else would, he’s not merely joined the establishment on the inside, he has become the establishment. And looking at him, there in that Union building, during those fleeting moments as he answered my question, looking at his jacket, jeans and platform shoes, I knew this was never going to be an ‘insight’ into the King of Hollywood. It was simply going to be an interview with Robert Downey Jr.