I know why Emily had a reason to play a smaller role than the main one. Because she was several months pregnant with first child. You could see her growing belly. She hid her pregnancy all the time. Her daughter was born in November 2005.
Filming date began in June 2005.
Review of Crusade in Jeans
Crusade in Jeans
(2006)
Nice movie, about secretly hidde real-life pregnancy of Emily Watson
22 June 2019