Keira Knightley's famous 'Love Actually' hat was a last minute addition.

The 33-year-old actress - who starred in the 2003 Christmas romantic comedy - has revealed that the scene where her alter-ego, Juliet, realises Mark (Andrew Lincoln) is in love with her, was actually fronted by a last minute wardrobe change because she got the ''biggest'' pimple of her ''life'' the morning of shooting.

Appearing on 'The Tonight Show Starring Jimmy Fallon', she said: ''Do you know what, the only thing I really remember from doing the whole of Love Actually, I was 17, and I got the biggest zit of my life when we were shooting this scene and it was the important one and it was literally like another head growing out of my head and it was a small part and I was only on it for two weeks and the chances of getting this extra head ... So they went in and they tried to cover it and they tried to light it but there was nothing they could do so the hat went on. That's the reason for the hat.''

The actress shot to fame as a teenager with roles in movies like 'Love Actually' but said criticism over her career and her changing body left her ''broken'', and eventually led to her suffering a mental breakdown when she was just 22 years old.

She said: ''I was at a time in my life when I was still becoming. Like most young people, I hadn't quite found who I was or what I was about. My body was changing, and I didn't even know how I felt about myself and what I looked like. Yet all of a sudden, people were being very vocal with their views on me as a young woman and as an actress. I lost confidence in myself because I was made to feel that I didn't deserve to be doing what I was doing.''