Stuart McDouall is one of six children born into an army family in 1950, joined the Royal Hong Kong Police as a probationary inspector at the tail-end of 1970, aged twenty-one.

In a career spanning 35 years, McDouall worked in several different spheres of policing, beginning with shift work as a duty officer and taking charge of a divisional patrol unit. He graduated from detective training and spent the next twenty years in the Criminal Investigation Department (CID), principally in the Triad Society, Criminal Intelligence and Narcotics Bureaus. In 1997, at the time when the sovereignty of Hong Kong was returned to the People's Republic of China, McDouall was acting Chief Superintendent in charge of the Police Training School.

Retiring from active service in 2005, McDouall obtained a diploma in education and took up teaching in a secondary school for a while. At the same time he was in charge of the English-speaking Scout groups in Hong Kong.