At Edinburgh he distinguished himself by winning the Ettles prize for medicine and the Goodsir Fellowship and worked as an assistant to Richard Fraser, professor of Materia Medica.

In 1884 Hay was offered and accepted the chair of pharmacology and therapeutics at Johns Hopkins University medical school, Baltimore.

Central to his vision for a healthier community was the bringing together of health services for the public with a medical school on the one site, and in 1900 he pinpointed the barren slope of Foresterhill outside the city centre as the ideal location for his dream.

[5] Glasgow, Edinburgh and Aberdeen were exceptionally represented by three pioneering Medical Officers: James Burn Russell, Henry Littlejohn and Matthew Hay.

The fact that Hay is not remembered today should not detract from his valuable contribution to the development of public health and Aberdeen's programme of urban regeneration.

For example, in 1902, mid way into his term as Medical Officer, Hay presented a paper on the Glasgow Corporation Water and City Improvements Bill.

In doing so, he spoke about the housing problem in Aberdeen where the city had closed slums down too rapidly without finding alternative accommodation for the displaced occupants.

This is an overly simplistic approach because it is based on an a priori assumption that ideas can be neatly compartmentalised and that their life span can be clearly delineated.

Instead there was a gradual development where different ideologies competed for supremacy as the ‘definitive’ tools for shaping social policy and for understanding the human condition and the nature of society.

Unemployment and poverty began to be viewed not so much in Benthamite terms as an individual self-inflicted and morally questionable condition but the product of impersonal economic forces.

By contrast, the inner city areas were turned into chronically overcrowded centres of insanitary housing unable to cope with the huge influx of people.

Programmes of slum clearance were principally concerned with the effects of the poor living conditions on the moral, physical, social and economic well-being of society.

The late Victorians and Edwardians believed that lifestyles and living conditions were linked and they feared that the respectable poor would be contaminated by their close proximity to the residuum in the slums.

The slums were believed to breed disease, crime, intemperance and immorality, external costs borne by wider society rather than the landlords and tenants of these properties.

Writing about the moral evils of London's ‘rookeries’ in the 1880s, Andrew Mearns (who was widely read by the Scottish middle classes) observed: "Few who will read these pages have any conception of what these pestilential human rookeries are, where tens of thousands are crowded together amidst horrors which call to mind what we have heard of the middle passage of the slave ship... “Marriage”, it has been said, “as an institution, is not fashionable in these districts”...

Through his tireless efforts and scientifically based reports Hay was able to persuade the Town Council to depart from its traditional, individualist, laissez faire view of the causes poverty (consistent with the social theories of Thomas Chalmers and Malthus) and to adopt the principles of municipal socialism in producing a workable model for solving Aberdeen's working class housing crisis.