Mumbai: At 92, when most professionals, even the passionate among them, would have shuttered their work, Shirish B Patel was still at it.

One of his last emails to me, among the many received over the decades, detailed why the proposed redevelopment of the BDD Chawls in Worli would take Mumbai further down the slippery slope.

He had consistently argued that "builder-driven slum redevelopment" would not change the lives of the Mumbai's poorest. In cities across India, as unequal in multiple ways as Mumbai, Patel argued that land for low-income housing should be taken off the market mechanism that had come to determine property-housing prices and availability in the post-liberalized city.

As Patel passes into the ages, quietly this Friday morning, it is difficult to acknowledge that there will be significant discussions and debates about planning and architecture in Mumbai, or cities in general, in which his deep measured voice or detailed words will be absent. One could agree with him, one could disagree with him about his assertions, but the engagement was important to conversations about the city.

For example, Patel was clear that there should be a common density across Mumbai - a proposition many disagreed with. Like most secure professionals, he did not take it amiss if he was contradicted or engaged in a debate. And, to the best of my knowledge, he usually gave his time and expertise to those who sought his opinion.

Although Mumbai's world of urban planning will miss him, he leaves behind an enviable oeuvre of work and an old-world approach to it that valued timeliness, meticu-lousness, commitment to values, and a deep engagement with the city that was not limited by personal ambitions or successes. Born in 1932, Patel's career spanned over six decades, during which he made significant contributions to India's infrastructure and urban planning.

An engineering graduate from the prestigious University of Cambridge, he established his own civil engineering firm, Shirish Patel & Associates (SPA), and successfully ran it. In the 1960s, he collaborated with architects and planners Pravina Mehta and Charles Correa to conceptualize the creation of a new city on pristine land across the harbor to ease the congestion in Mumbai. This city, as most people know, became New Bombay, now christened Navi Mumbai.

Patel served as an advisor and later as the director of planning and works at the City and Industrial Development Corporation (CIDCO), which spearheaded the development of the new city.

The flyover at Kemps Corner, the first in India, carries Patel's stamp as do the Kariba and Koyna dams, and a host of private and commercial buildings in Mumbai. It was Patel's constant engagement with core urban issues, irrespective of how it was received in the corridors of power or boardrooms of the wealthy, which made him both an instrument of change and its critic.

Rather, the other way around. What he critiqued Mumbai's development trajectory, he sought to change it too. He wrote in media and spoke at platforms of his choice making cogent and forceful arguments about Floor Space Index, density, slum redevelopment, Dharavi, BDD Chawls, coastal road, recycling industrial land and more. In fact, his last set of co-authored books was published only last year - a two-volume set titled 6 Metros.

In a recent interview with sociologist Hussain Indorewala, Patel bemoaned that "there is no real protection of public interest anymore on the part of the bureaucracy," lamenting that the coastal road was in "motorcar interest, not in public interest". An old-world Mumbai lover and planner has departed from this world - after leaving his imprint on the city.