Sir Donald Insall, architect behind Windsor Castle restoration, dies at 100

Sir Donald Insall, the architect known for conserving and restoring historic buildings including Windsor Castle, has died at the age of 100.

His studio, Donald Insall Associates, announced his death in a statement. The news was reported by Dezeen on 13 October 2026.

Insall was born in Bristol, England, on 7 February 1926. He set up his own practice in 1958 and served as its chairman until 1998. Conservation, the careful repair and reuse of old buildings, was the core of his work.

He was closely linked with Windsor Castle in Berkshire, the royal residence west of London. After fire devastated the castle in 1992, Insall led the teams that restored the building. It was painstaking work. The job required matching historic craft with modern safety and use.

That Windsor commission came from a long career spent on old places rather than new ones. Insall built his name on surveys, repairs and renovations that kept historic structures in daily use, rather than freezing them as exhibits.

He also helped shape the system that protects such buildings. Insall was a founding commissioner of English Heritage, the charity that looks after historic sites across England and advises on listed buildings. Commissioners oversee its strategy and public responsibilities.

Alongside running a practice, he worked as a town planner and planning consultant, advising on how towns and sites should grow and change. He also worked as an author, according to Building. His studio described him as a town planner in its announcement, shared on LinkedIn.

He held the title Sir and the honour CBE, Commander of the Order of the British Empire, a British state honour for public service. The studio used both titles in announcing his death.

Insall lived to 100. His practice continues under his name.