IN BRIEF: Liverpool's saviour appalled by city mortality rates.
He graduated from Edinburgh University in 1829 and returned to Liverpool to establish himself in general practice and lecture in medical jurisprudence.
But his break into the limelight of Victorian politics came in 1844 when he wrote a controversial report to the town council damning the dreadful condition of Liverpool's slums.
Appalled by the high rates of mortality caused by the dismal state of housing and lack of sanitation in the poorer districts, Dr Duncan demanded changes in the city's public health policy.
Despite fierce resistance, he persuaded the council to order the cleansing of infested houses, courts and cellars to kill parasites and cockroaches.
A year later, Dr Duncan was appointed Liverpool's first medical officer of health - the first role of its kind in Britain - and began creating a public health service.
His appointment coincided with an influx of Irish peasants fleeing the potato famine.