She is best known for her roles as Jem Walker in the BBC Three series In the Flesh (2013–2014) and Philippa Featherington in the Netflix period drama Bridgerton (2020–).
She took acting classes at a drama club called Circle Up for three years before going on to train at the Television Workshop.
[3] To prepare for the role, Cains watched documentaries about post-traumatic stress disorder and anxiety while also talking to people with experience to portray them in a realistic manner.
[5] Since 2016, she has appeared in various supporting roles, including Lizzie Hallum for the crime series Vera[6] and Jade Hopkirk in Line of Duty in early 2017.
[9] In 2019, Cains was as cast as Philippa Featherington in the 2020 Shondaland and Netflix period drama Bridgerton, based on the books by Julia Quinn.