He was a man with a missionary zeal, working tirelessly for more than 40 years at the Australian National University to highlight the significance of town planning as a crucial part of the development of Australian cities, emphasising the roles of federal and state governments in providing infrastructure and essential services generally, and of public transport and affordable housing in particular.

Town planning is basically an ideology. It's the belief that cities can be made more comfortable, attractive, environmentally sensitive, aesthetically pleasing and functionally affordable, and be better laid out. Its fundamental aim is to produce liveable cities, as distinct from blindly leaving everything to the vagaries of the market.

Because of its somewhat "other world" nature, town planning needs to be constantly refreshed and advocated so that governments adopt it as the preferred way to help cities cope with growth and change. Troy engaged in this mission in with vigour and persistence throughout his career, as a civil engineer, town planner, educator and urban researcher.

He was successful in a practical sense because he became a confidant of politicians, even prime ministers. They invariably regarded his motives as disinterested, professionally informed, socially concerned and expert in dealing with the complexities of urban development and their effects on government budgets at a time cities worldwide were predominantly becoming a civil-engineering artefact.

Troy was influential in establishing the Department of Urban and Regional Development during the Whitlam government (1972-1975), which drew the Commonwealth for the first time into the realms of city and regional planning; until then, they had been the exclusive responsibility of state and local governments. He was the department's deputy secretary for three years until the Fraser government closed it in 1975. Troy went on to spend the next four decades at the ANU, ending up as the professorial head of its urban research unit/program. He became an emeritus professor when he retired in 2006.

His output as an academic, beginning in 1965, was prodigious: a stream of books, pamphlets and learned articles. In the last 15 years, for example, more than 50 of his works were published, most after his retirement. His role as a facilitator in urban studies led to a new understanding of the role of government in urban and regional reform, along with fields such as social justice and environmental studies, with particular emphasis on metro-transport and public housing.

He initated and sponsored collaborative urban research in Australian universities, and had an unusual capacity to build links between researchers and government agencies; all the time looking for opportunities to nurture the careers of others. His research and writing never stopped, focusing always on the social and environmental questions of the times in urban policy and planning. This was acknowledged when he became a fellow of the Academy of Social Sciences in Australia.

His father, Patrick (Paddy) Troy (1908-1978), founded the Western Australian Trades and Labour Council (1963) and was an ALP "hero" in the period 1935 to 1970, who enjoyed the respect of employers and the trust of his union. Well before his time, Paddy was a strong supporter of Aboriginal emancipation. For these reasons, Paddy was a significant influence and source of pride in his son's life.

The younger Troy was a civil engineer (because he was good at maths) who became a town planner; he didn't want to practise planning but wanted to understand it as a route to improving society. He finally became an educator so that, in universities, he could encourage graduates to become aware of how the development of cities and regions gives rise to fundamental needs for housing, schools, hospitals and public transport, which are not always delivered for the less well-off. As a consequence, providing these services needed to become a cause and a course of action.

Troy was ultimately a missionary, a pursuer of causes, a seeker of solutions and a tireless traveller to universities and associations around Australia, fostering groups interested, like him, in making better cities.