Molly Marsh read music at Girton College, Cambridge and later completed postgraduate studies in baroque and classical oboe at both the Royal Academy of Music (Sophia McKenna) and the Conservatorium van Amsterdam (Alfredo Bernardini). In 2000, while still a student at the RAM, Molly was invited to play Principal Oboe with the European Union Baroque Orchestra, with whom also performed as a soloist. Since then, she has performed and recorded with many of Europe's top period instrument ensembles. She is a regular member of The King's Consort (Robert King), Europa Galante (Fabio Biondi) and Das Neue Orchester (Christoph Spering) and has played with many others, including English Baroque Soloists, Ensemble Sonnerie and The Dutch Bach Society. She is also a committed chamber musician and in addition to the Etesian Ensemble is a member of the London based baroque ensemble Abendmusik.

Molly enjoys exploring a wide range of repertoire on period instruments, from baroque to early romantic music. For the repertoire performed by the Etesian Ensemble, she uses a 2-keyed classical oboe by Alfredo Bernardini (2002) after Grundmann & Floth (c.1795).