Henry Thomas Marsh was born 5 March 1950. Marsh attended the Dragon School in Oxford and Westminster School in London. Later he studied Politics, Philosophy and Economics at University College, Oxford University, achieving First Class Honours, before graduating with Honours in Medicine from the Royal Free Medical School.

Marsh is a leading English neurosurgeon, and a pioneer of neurosurgical advances in Ukraine. Until 2015, Marsh was the senior consultant neurosurgeon at the Atkinson Morley Wing at St George’s Hospital in south London, one of the country’s largest specialist brain surgery units.

He specialises in operating on the brain under local anaesthetic and was the subject of a major BBC documentary Your Life in Their Hands in 2004, which won the Royal Television Society Gold Medal.

He has a particular interest in the influence of hospital buildings and design on patient outcomes and staff morale; he has broadcast and lectured widely on this subject.

In 2017, Marsh published Admissions: Life as a Brain Surgeon, a second memoir with Weidenfeld & Nicolson, an imprint of Orion.