Cameron insists she will never forget the support the 'Iron Man' star gave her.
In an interview with the June UK issue of Harper's Bazaar magazine, she said: "We became very close after my dad's death. She reached out and it was very sweet. We bonded on that."
The 39-year-old actress also revealed she is an Anglophile and loves Englishmen because she grew up watching British comedy TV shows like 'Monty Python's Flying Circus'.
Cameron - who has previously dated Justin Timberlake, and baseball Alex Rodriguez and has been linked to rapper P. Diddy - thinks Colin Firth is the "perfect Englishman".
She said: "I love their (English guys') sense of humour and the sense of chivalry and charm. It's something that is innately a part of the culture - we don't have that over here, it's not the same in America.
"(Colin Firth) is the perfect Englishman. Just enough of the self-effacing to a point that it's comfortable for other people, but also totally charming and engaging to where he makes you feel special.
"I love London. I love the Brits, I always have. I have a weak spot for them. I grew up on 'Monty Python'. I love 'Little Britain'. My grandfather used to watch Benny Hill all the time."