Sir Donald Insall Dies at 100, Leaving a Lasting Legacy in Architectural Conservation

Sir Donald Insall, the British architect and conservationist whose work helped shape the modern approach to historic building restoration, has died at the age of 100. His death was announced in October 2026 by Donald Insall Associates, the architectural practice he founded in 1958 with fellow architect Peter Locke.

Insall's career spanned decades of work on historic buildings, urban conservation and heritage policy. Among the best-known projects associated with his practice was the restoration of Windsor Castle following the devastating fire of 1992. His wider portfolio included the conservation of Chester's historic center, work at Kelmscott Manor and the restoration of other significant British buildings.

Beyond individual projects, Insall helped establish an approach to conservation that considered how historic places could remain useful while retaining their architectural and cultural significance.

His passing marks the loss of a prominent figure in British architectural conservation, a discipline he helped develop through professional practice, research, teaching and writing.

A Career Dedicated to Historic Buildings

Born in Bristol on February 7, 1926, Insall grew up in a family involved in the manufacture of leather goods, trunks and portmanteaus. This early exposure to craftsmanship would become relevant to a career centered on understanding buildings, their materials and the skills required to maintain them.

He studied architecture at the Royal West of England Academy School of Architecture from 1942 to 1948 before continuing his education in civic design and planning in London.

Insall later became a Lethaby Scholar with the Society for the Protection of Ancient Buildings, an organization founded by William Morris in 1877. There, he developed a professional interest in the practical and philosophical questions surrounding historic building care.

He and Peter Locke established Donald Insall Associates in 1958. The practice would become known for its work on historic buildings, conservation planning and the adaptation of existing structures for contemporary use.

One of Insall's central concerns was the distinction between preserving a building exactly as it was and conserving it in a way that allowed it to remain part of everyday life.

His approach recognized that historic structures inevitably change over time. The challenge, as he saw it, was to manage that change carefully, maintaining the qualities that made a building significant while addressing the needs of its occupants.

Windsor Castle Restoration Became a Defining Project

The fire at Windsor Castle in November 1992 caused extensive damage to one of Britain's most recognizable historic buildings. The subsequent restoration required architects, specialists, craftspeople and builders to assess the damage and develop a strategy for recovering the affected areas.

Donald Insall Associates played a significant role in the restoration effort. The project involved a range of approaches, from repairing and reconstructing damaged interiors to restoring the architectural character of historic spaces.

The work demonstrated the complexity of conserving a major historic building after a serious incident. Decisions had to account for surviving fabric, historical evidence, structural requirements and the need to return the castle to use.

The restoration also illustrated an important principle associated with Insall's philosophy: conservation does not necessarily mean freezing a building at a single moment in history. Instead, it requires informed decisions about what to retain, what to repair and how to accommodate the future.

The practice's other projects reflected a similar concern for balancing architectural heritage with continued use.

At Kelmscott Manor in Oxfordshire, associated with designer and writer William Morris, conservation work addressed the historic character of the property. In Chester, the firm's study of the historic city helped establish a broader framework for considering conservation at an urban scale.

These projects demonstrated that heritage protection extends beyond individual monuments. Streets, neighborhoods and the relationships between buildings can also carry historical significance.

Insall Helped Shape Modern Conservation Principles

Insall's contribution extended beyond project delivery. Through reports, books and professional work, he helped communicate conservation principles to architects, planners and the wider public.

His 1957 report, The Care of Old Buildings, established an early foundation for his writing on the subject. He later published The Care of Old Buildings Today: A Practical Guide in 1972 and Living Buildings: Architectural Conservation, Philosophy, Principles and Practice in 2008.

These works explored the practical and philosophical questions involved in maintaining historic structures. They also reflected his belief that conservation required a detailed understanding of a building's history, construction and surroundings.

Rather than approaching every historic property through a fixed formula, Insall advocated examining the building's individual characteristics, identifying what deserved protection and considering how its current users could continue to occupy it.

This method is particularly relevant to adaptive reuse, in which existing buildings are given new functions while retaining significant architectural elements. It requires a careful assessment of materials, structural conditions, historical value and the demands of contemporary use.

His influence also extended to the planning system. Insall became a founding commissioner of English Heritage in 1984, contributing to the development of institutions concerned with protecting England's historic environment.

His professional achievements were recognized through several honors. He received an OBE in 1981, a CBE in 1995 and a knighthood in 2010.

Insall retired as chairman of his practice in 1998 but continued to serve as a consultant.

A Lasting Influence on Architectural Heritage

Insall's career helped establish architectural conservation as a discipline that requires both technical expertise and a broader understanding of cultural history.

The restoration of Windsor Castle remains a prominent example of the work associated with his practice, but his legacy also lies in the principles he advanced: understanding buildings before intervening, respecting their historical character and recognizing that continued use can be essential to their survival.

These ideas remain relevant as cities and property owners consider how to maintain aging buildings, adapt historic structures and respond to changing environmental and functional requirements.

Conservation architects must often negotiate between the demands of preservation, modern building standards, accessibility and the practical needs of occupants. Insall's work helped demonstrate that these concerns need not be treated as mutually exclusive.

By combining architectural practice with research, writing and institutional involvement, he contributed to a lasting shift in how historic buildings are understood and managed.

Sir Donald Insall leaves behind a body of work that reflects a central principle of architectural conservation: historic places can remain meaningful when their past is respected and their future is carefully considered.