(Cover) - EN Showbiz - Elisabeth Moss was relieved to find Keira Knightley was as cool as shed expected when they began working together.

The two stars appear alongside each other in a new version of Lillian Hellmans play The Childrens Hour, which is being staged in London later this month. The story is about two women who set up a school together in the 1930s and are then accused of having an affair.

Elisabeth was thrilled when she heard Keira, 25, had accepted a role, explaining she knew the two would get on well.

She is absolutely lovely, Elisabeth said. She really is, and I had a suspicion that she would be. Shes a huge movie star. You dont have to do theatre at her age. The fact that she committed to this really difficult play for five months was a big clue about her character - she must be cool.

Elisabeth is best known for her portrayal of Peggy Olson in American television show Mad Men. She is more than happy to discuss her work on the programme, but is much less open when it comes to her private life.

The 28-year-old filed for divorce from Fred Armisen last October, less than a year after they married. Neither side has discussed the reasons for the split, although there have been many rumours about why the relationship ended. Elisabeth found the speculation intensely painful, which is why she has vowed to keep her personal life private from now on.

I found that my private life was more in the public eye than Id ever experienced, so I decided to make a nice little rule for myself that if I wanted to keep it out of the public eye, I would, she told Culture magazine. I just dont talk about it. Im a very nice person, so I dont want to be rude, but theres a danger to talking about your personal life too much. (C) Cover Media