The actress was pregnant for one pivotal scene in the period movie, in which her landscape gardener character has to plug a flooding stream, and she took it into her own hands to make sure the water was the perfect temperature for her without ruining pal Alan Rickman's directorial debut.

She tells WENN, "I was absolutely fine in the water. It was warm and at night and it wasn't cold so it was like getting into a big bath. I was bossing everyone around and they were like, 'Kate, we've really warmed the water for you'. I was like, 'Well, what temperature have you warmed that water to because if it's too warm, it's like getting into a hot tub and we're not supposed to get into hot tubs too long any of us, let alone pregnant women'.

"I said, 'You're gonna have to change the temperature. Plus, when you turn on those rain towers and the cold water hits warm water you're gonna get steam which you don't want, because this is supposed to be a river!'

"Sure enough, they did a test and there was steam everywhere. I said, 'Told you!' Dare I say it but I did learn that on Titanic."