During WWI he attempted to enlist in the British Army but he was graded as medically unfit because of his severe psoriasis.
He held a house appointment in Liverpool for about a year and then in March 1921 joined the staff of London's National Hospital for Nervous Diseases.
Since most of his work was clinical his reputation depended on sound observation leading to accurate diagnosis and selective treatment and was not to be found through lengthy lists of publications but rather embodied as a corpus of experience in his invited contributions, such as the 8th and especially the (1956) 9th editions of the magisterial (Price's) Textbook of Medicine.
[7]Martin's book The Basal Ganglia and Posture (1967) includes case histories and clinical observations of a large group of patients with post-encephalitic Parkinsonism who were long-stay patients at Highlands Hospital, Winchmore Hill.
[10] Oliver Sacks, an American professor of neurology, wrote: 'Purdon Martin was endlessly thoughtful and ingenious in designing a variety of mechanisms and methods that made it possible for even the most incapacitated patient with Parkinsonism to achieve an artificial normality in gait and posture; lines painted on the floor, counterweights in the belt, loudly ticking pacemakers to set the cadence for walking, and these he always learned from his patients to whom his great book is dedicated.