Saoirse Ronan thinks it's "mad" that 'Lady Bird' has become such a success.

Saoirse Ronan

Saoirse Ronan

The 23-year-old actress stars as teenager Christine in the new movie by Greta Gerwig, and the coming-of-age drama has been nominated for Best Picture at this year's Academy Awards.

It was named Best Motion Picture - Musical or Comedy at the recent Golden Globes and Ronan was chosen as the winner of Best Actress - Motion Picture Musical or Comedy and she is simply staggered that this "tiny little film" has done so well.

Speaking on 'The Graham Norton Show' - to air on BBC One on Friday night (09.02.18) - Ronan said: "It's great. It's mad that it's done so well. It was a tiny little film that's become such a big commercial hit. It's really nice."

'Lady Bird' - which saw the film take home the Golden Globe for Best Film - follows outspoken teenager Christine (Ronan) who must navigate a loving but turbulent relationship with her strong-willed mother over the course of an eventful and poignant senior year of high school.

In order to get back into the mind of a 17-year-old girl, Ronan revealed she watched a lot of TV shows based around teenage characters.

She said: "I watched a lot of 'Saved by the Bell' and 'Sabrina the Teenage Witch'."

Ronan has also been nominated for Best Actress at Oscars and admitted she forgot that the nominations were being announced.

She said: "I'd actually forgotten that they were coming out - it had gone completely out of my head."

The actress - who was also joined on the iconic sofa by 'Will and Grace' stars Eric McCormack and Debra Messing, as well as comedian Rob Beckett and singer Keala Settle - also recalled taking her mum to see her latest movie in the cinema.

She said: "My mam is very proud of me and I wanted her to see the film as part of a real audience so we went to an afternoon performance in LA. I thought it would be sold out and warned her to keep her head down so we weren't recognised. When we got in there, there were six other people ... all on their phones! No one was interested in us at all."