Colin Firth: Kidman is my work wife
The pair have already played husband and wife in The Railway Man and in upcoming thriller Before I Go To Sleep, and also both have roles in the new Paddington Bear movie.
Colin told the newspaper at a screening of The Railway Man in New York: "Once you develop a connection with somebody, it helps you from job to job.
"I think her versatility is extraordinary. It's not just about the extraordinary results she produces, but also the choices she makes are a testament to the kind of mentality she has."
Asked if Nicole was his 'work wife' Colin said: "That's not too off base to describe it that way. I hope it goes on forever."