Alison Steadman and Mike Leigh never discussed work at home.
The actress - who married the director in 1973 and split from him in 1995 - starred in several of the helmsman's movies but admitted it was an important rule in their relationship to leave filming behind when they wrapped for the day.
She said: "I think one of the rules was always that we never discussed the work at home. "There's enough discussion going on when we were working, and we were working usually 'til 11 at night, starting at seven in the morning, so there wasn't realy time.
"But there was an unspoken rule that we didn't discuss the work because that would have been off limits."
Mike had the cast of his films keep their scripts secret and Alison admits this meant even she received surprised when watching her finished work.
Speaking about her role as working mother Wendy in 'Life Is Sweet', she said: "There's the scene where Wendy comes home and [her daughter] Nicola is washing her sheets again. I thought, as Alison and therefore also as Wendy, that it was because she had something like OCD [obsessive compulsive disorder], where they can't stop washing - but it was only when I saw the film finished that I found out it was because of what she'd been doing with the boyfriends and the chocolate and the sheets, so that was a real shock to me because I'd had no idea."
Alison was talking in conversation with Lauren Laverne at a special Rooftop Film Club screening of 'Life Is Sweet' to launch the American Express Preferred Seating Programme 2012.