Cate Blanchett's Upton certainty

Cate Blanchett "couldn't not" say yes when her husband Andrew Upton proposed to her.

The 39-year-old actress - who has three sons, seven-year-old Dashiell, four-year-old Roman and eight-month-old Ignatius with Andrew - knew she would end up marrying the playwright as soon as they met.

Speaking about Andrew's proposal, Cate said: "I couldn't not accept. We were in exactly the same place at exactly the same time. He turned to me after a few days and said, 'Cate … ,' and I thought, 'Oh, god, he's going to ask me to marry him - and I'm going to have to say yes!' He didn't, in fact - he asked me what I wanted for dinner or something like that. But I'd never had that thought before. I thought, 'This is extraordinary! I've never felt this before. What an adventure!' "

Cate - who can next be seen starring alongside Brad Pitt in reverse ageing movie 'The Curious Case of Benjamin Button' - also revealed while she and Andrew are happy in their relationship, there is one thing that would spark problems between them.

She added to Vanity Fair magazine: "Andrew said he'd divorce me if I had any plastic surgeries.

"When you've had children, your body changes, there's history to it. I like the evolution of that history. I'm fortunate to be with somebody who likes the evolution of that history."