Claim: Lily James was in Just William as Ethel Brown.

Lily Chloe Ninette Thomson -LRB- born 5 April 1989 -RRB- , known as Lily James , is an English actress . She played Lady Rose Aldridge in the ITV period drama Downton Abbey and the title role in the 2015 Disney film Cinderella .   James began her professional acting career as Ethel Brown in the 2010 BBC production Just William . In 2011 and 2012 , she earned warm reviews in several London theatre productions . She began to appear in Hollywood films in 2012 , with roles in Wrath of the Titans and Fast Girls , and was seen in further television roles , including that of Countess Natasha Rostova in the 2016 BBC historical drama series War & Peace .