He was responsible for the introduction of apomorphine to treat advanced complications of Parkinson's disease including L-dopa induced refractory off periods and dyskinesias.

Other achievements include: Council Member for the Academy of Medical Sciences, United Kingdom,[11] National Institute for Health and Care Research (NIHR) Senior investigator,[12] Co-founder and past President of The Movement Disorder Society, Founding Editor of Behavioural Neurology (1988- 1993), Former Co-Editor-in-Chief of the journal Movement Disorders, UK Government National Institute for Health and Care Excellence Guidleline Development Group for Parkinson's Disease (2016-2019),[13] Visiting Professor to the Hospital Sao Rafaele, Salvador Brazil, Honorary overseas member of the Academia Nacional de Medicina, Brazil.

[1][2] In addition to his academic career Lees has written a book about the city of Liverpool[17] and the authorized biography of footballer Ray Kennedy.

[20][21] Lees was a longstanding friend[22][23] of Oliver Sacks, who also began his neurological training at the Middlesex Hospital ]], and he was acknowledged in the preface of Sacks books Awakenings,[24] a story about L-dopa treatment of encephalitis lethargica which was made into a film starring Robert De Niro and Robin Williams, and The Island of the Colorblind,[25] which deals with parkinsonism caused by Lytico-bodig disease.

In his memoir 'Mentored by a Madman' and 'Brainspotting' Lees explains how his career was influenced by Arthur Conan Doyle's character Sherlock Holmes and by the self-experimentation of William S. Burroughs, author of Naked Lunch.