THEY MAY be lining up against each other on-screen but the team behind Captain America: Civil War couldn’t be a tighter, more jovial bunch in real-life.

In London to promote the latest entry into the Marvel universe, lead actors Robert Downey Jr and Chris Evans – aka Iron Man and Captain America – took the stage with some of their colleagues for a veritable orgy of back-slapping rather than attempting to stoke any film-based rivalry.

Evans, for instance, spoke of his excitement at first reading the script for Civil War, which pits two of the franchise’s most iconic characters against each over plans to make superheroes more accountable.

“A lot of it rested on Downey’s shoulders and whether or not he would be willing to do this,” he said. “But you know right away that if you bring him into the equation, the movie is going to have a certain level of awareness and charisma. That’s what he brings.

“So, you knew what it meant as a jump-off because obviously Civil War incorporates so many different characters. What’s more, Marvel has this great history of never leaving you completely satisfied, but anticipating the next chapter, so this would leave the entire universe in a little bit of disarray. And that was exciting because it’s only going to make the next Avengers richer.”

Downey Jr was equally as effusive. Asked how much of the evolution of the franchise and its characters were down to him, given his involvement in launching the universe with the original Iron Man in 2008, he replied: “[Marvel Studios President Kevin] Feige and I were out to dinner last night and were looking back at the last 10 years and all the little miracles and blood, sweat and tears that had to happen to keep developing all of these characters, and we just kind of – not in a self-aggrandising kind of way – but we were just super, super grateful at how things have gone.

“But I do have to say that I think [screenwriter] Christopher Markus did an exceptional job on this, which was a really tall order.”

If that sounds generous, then consider the elements that have gone into the film. For the centre-piece battle alone, there are no fewer than 12 superheroes on-screen at the same time, including two newcomers in Spider-Man and Black Panther. It’s taken years of planning to get all the pieces aligned.

“The chess board on this movie was 'who sides with who?' And there were a lot of characters that went back and forth before landing on either side,” explains Feige. “In terms of the addition of Tom Holland as Spider-Man and Chadwick Boseman as Black Panther, it came from the story.

“We didn’t just sit down and go, ‘OK, we want to introduce these characters because we want to make more movies and we have to wedge them in’. In the case of the latter, we had Cap’s side and Tony’s side and we wanted to bring in somebody who wasn’t aligned with either.

“Black Panther in the comics was great because he doesn’t really care about either side. He has his own agenda. So, it wasn’t until a quarter of the way through the filming process that we thought this would be the time to bring him in.”

Talk of the new Spider-Man brings Downey Jr back. Describing young British actor Holland as "really something else", he adds: “He came in with a bang and I think there’s now a lot of excitement about what will happen when he kind of holds his own [in next year’s Spider-Man: Homecoming].”

And so the gushing continues. When Evans recalls a stunt involving a helicopter that left him with a bad arm, it was Downey Jr that offered assistance.

“I genuinely did mess up something in my arm while holding onto that helicopter,” he said. “So, there were many days when I would go to Downey’s trailer where he has all these amazing contraptions. He’s like... I’m not going to say it because we don’t want to bring DC [Comics] into it! But he really helped me out.”

Ironically, it’s talk of on-location trailers that brings about the first hint of rivalry. Anthony Mackie, who plays The Falcon, had the biggest - but Downey Jr had five.

It was left to the movie’s main villain, Daniel Bruhl, to deliver an anecdote of on-set rivalry: “On the first day of working with Robert, he asked me if I had allergies. I didn’t understand the question at first. But when I was having my burrito in my humble little trailer, there was a knock at my door and I was cordially invited to Robert Downey’s village! I didn’t know what he was talking about but then, in the far distance, I saw this huge space with four or five trailers. I had a three-course meal and was quite sad when he left.”

Adds Mackie: “That was everybody’s goal, every day, to see who was going to be invited. You’d get so jealous. The day Daniel was invited I was sitting in my trailer going ‘mother-f****r!’”

Finally, a chink in the armour of the nicest bunch of superheroes in the cinematic galaxy.

Captain America: Civil War opens in cinemas today