Robert Downey says he was 'den mother' on Avengers set

LONDON — It is hard to imagine Robert Downey Jr as the authoritarian type, but the actor says he played a stabilising force amid the ever-growing cast of superheroes during the filming of Avengers: Age of Ultron.

"I am an assistant den mother for him (director Joss Whedon) — we're more contemporaries," Downey said at the film's London premiere yesterday (April 21), where he was accompanied by others in the cast, including Scarlett Johansson, Chris Hemsworth and Mark Ruffalo.

"With some younger talent, they're very exuberant; I remember when I was that way. I kind of feel like I'm the assistant principal."

The 50-year-old Downey plays Iron Man in the film, the sequel to the 2012 blockbuster Avengers movie.

For Johansson, the screen reunion was "amazing".

"I mean first of all it's great to be able to share this experience with actors that are really friends of mine and it feels like we're all in it together," said the actress, who plays Black Widow. "We're all a part of something that has this huge fan base, this built-in excitement and it's not always like that."

New this time are Aaron Taylor Johnson and Elizabeth Olsen, as Quicksilver and Scarlet Witch, respectively.

"They've already done the work of establishing a fan base," smiled Olsen, "so I feel like I've snuck in."

This is Whedon's last Avengers movie — at least for now. He will hand over the reins of the franchise to Captain America: Winter Soldier directors Anthony Russo and Joe Russo for the two-part Avengers: Infinity War, due out in 2018 and 2019.

The director admits he has mixed feelings about saying goodbye.

"Yeah it's sort of like sending your kid off to college, it's like wow, they really don't need me anymore, do they?" he said, pretending to sob. "At the same time it's like, 'My kid's gone, party all night!' You know, I'm going to pick my actual kids up from school, I'm going to read books, it's going to get crazy."

Avengers: Age of Ultron is set to open in US theatres on May 1, but it is opening in other countries earlier. It opens tomorrow (April 23) in Singapore. AP