Also in 2006, she starred in the film Driving Lessons alongside Rupert Grint (who played her son Ron in the Harry Potter series), and later had a leading role in the BBC 's adaptation of Philip Pullman 's novel The Ruby in the Smoke.er other film roles include Personal Services (1987), Prick Up Your Ears (1987), Buster (1988), Stepping Out (1991), Calendar Girls (2003) and Mamma Mia! (2008). She has also played Molly Weasley in seven of the eight Harry Potter films (2001–2011).