[2] She attended Francis Holland School, Sloane Square.
[3] Waterstone became a member of the National Youth Theatre when she was thirteen, and later took a one-year foundation course at the Cambridge School of Visual and Performing Arts before moving on to her acting career.
[4] Waterstone started her professional career on stage at The Pleasance Theatre, Islington, as Lucy/Nibs in the original production of Peter Pan Goes Wrong, followed by playing Susanna Walcott at The Old Vic in Yaël Farber's production of The Crucible,[4] and has also played Emma in Rules for Living at the Royal National Theatre.
[5] In 2014 she appeared as Katie Bowman in two episodes of the TV series Silent Witness, as Beatrice in the TV miniseries And Then There Were None,[5] and as Clare Leighton in Testament of Youth.
[7] From 2015 to 2019, Waterstone played the role of Margo Durrell, a main character in the family comedy drama series The Durrells which ran for four series finishing in May 2019.