How many movies have Colin Firth and Zara Treherne acted in together?

They have worked on 2 movies together! Their first movie together was St Trinian's 2: The Legend of Fritton's Gold (2009) while their highest rated movie together was Mamma Mia! Here We Go Again (2018). They have not worked together since Mamma Mia! Here We Go Again (2018).