In 1996, Marston made her debut appearance on television in the mini-series Neverwhere, playing the role of Anasthesia for two episodes, in a cast which included Tamsin Greig and Peter Capaldi.
[2] In 2004, Marston played Priscilla Stanbury in the 4-part BBC miniseries He Knew He Was Right alongside Bill Nighy, Geoffrey Palmer and David Tennant.
[4] In 2012, she appeared in the feature film Bel Ami in 2012,[5] alongside Christina Ricci, Kristin Scott Thomas and Uma Thurman.
[6] In 2019 she appeared in The Current War, alongside Benedict Cumberbatch, Michael Shannon and Nicholas Hoult.
[8] Marston was nominated for an Offie Award in 2018, for 'Best female in a play' for her role as Sylvia Gellburg in Broken Glass at the Watford Palace Theatre.