Marni most recently doubled for the role of Iris on Rain Dogs (HBO/BBC). 

She has appeared in Casualty (BBC), His Dark Materials (BBC) and Reconstruction (ITV). She also played an Elf in Elf the Musical and has filmed a commercial for Whitshire Farm Foods playing the granddaughter.

She speaks English and Welsh and is a very strong singer and dancer specialising in Ballet, Tap and Modern. She also plays the piano.