While studying for a degree from King's College London, she also spent time playing with Past Caring and was part of the squat gig scene with The Libertines, The Others and Left Hand.
Her past guests have included Alan McGee, Ian Broudie, Mark Collins from The Charlatans, and Elly Jackson, her friend and bandmate from La Roux.
Her work of note includes composing the score for Paul Sng's film documentary Dispossession: The Great Social Housing Swindle.
[4] O'Brien also provided the title music for the trailer of the launch of the book: Invisible Britain: Portraits of Hope and Resilience.
In January 2019, O'Brien composed a piece of music for British designer Edward Crutchley for his show at the Truman Brewery during London Fashion Week.