Robert Downey Jr. has made the comeback of the decade with huge success in such films as “Iron Man 3”, “Sherlock Holmes” and “Due Date”.

The 48-year-old star has played the role of Iron Man/Tony Stark in the superhero trilogy and 'The Avengers', and - if a two-film deal is reached for him to reprise the part in sequels to the comic book blockbuster - he could soon become the best-paid actor in the history of Hollywood.

While on the tour circuit for his flick, “Due Date”, the Irish American actor spoke about his pride in his heritage.

“I have Irish blood coursing through my veins. Every time I work in the UK, I’m always planning on a long weekend over there but it never works out,” he told the Sunday World magazine.

In 'Due Date' Downey plays businessman Peter Highman, a father-to-be who attempts to make a  dash to L.A. To be by his wife's side for the birth of their first child.

Peter's plans run into trouble when he is forced to travel alongside wannabe actor Ethan Tremblay (Hangover star, Zach Galifianakis) in what becomes an unforgettable road trip.

“Peter is like us, men and women who have real jobs, real anxiety and a real need to perform in society,” Downey explains.

“He runs into Ethan, this person who is really sweet and a complete gentleman but who cannot help pushing his buttons.

“I grew up watching these road trip movies, so the script really brought me back...I had a blast shooting with Zach