SIR CHARLES BRETT was the towering and tireless champion of Ulster’s architectural heritage over nearly half a century. He described himself in 18th-century terms as a provincial Irish attorney, the sixth generation of his family in a line of solicitors (now continued by his son) but early in his career joined the Northern Ireland Labour Party hoping to build up a constructive non-sectarian alternative to the Unionists. When his hopes finally collapsed in 1974 he observed: “There is no future in British or Irish politics for somebody who dislikes all forms of religion, all forms of sport and all kinds of pets.”

Charles Edward Bainbridge Brett was born in 1928. After school at Aysgarth in Yorkshire and Rugby he won a history scholarship to Oxford, where he attended Kenneth Clarke’s lectures on the Italian Renaissance, and was president of the University Poetry Society, visiting country pubs with Dylan Thomas, whom he one night wheeled home asleep in a large pram to Witney.

In 1949-50 he spent a formative spell in France (about which he frequently reminisced) working as a sub-editor and announcer for the English service of Radiodiffusion Française and for the Continental Daily Mail on the gossip columns, where a colleague covered the Duke of Windsor and he the low life of Montparnasse, making friends in anarchist and Trotskyite circles — sparking a lifelong interest in literature.

In 1956 Lord Antrim invited him to join the Northern Ireland committee of the National Trust. When Brett asked what books he should read to prepare himself Lord Antrim laughed, replying: “There are none”. Brett resolved to right this, starting work on the first serious architectural appreciation of Northern Ireland’s first city, an inventory of the Buildings of Belfast 1700-1914, which was published in 1967.

The next year he founded and became first chairman of the Ulster Architectural Heritage Society (other key figures were Alistair Rowan, Desmond Hodges and Dorinda, Lady Dunleath). The UAHS was created at a time when there was no statutory listing of historic buildings in Northern Ireland, no historic buildings council, no historic buildings grants and no counterpart of the National Monuments Records for England and Scotland. All these now exist thanks in considerable part to Brett’s drive and determination.

Brett served as chairman for the first ten years and then was president from 1979 until his death. He was always outspoken and always a stiffening influence in the society’s difficult relations with indifferent government departments.

For the National Trust his energy and legal skills were directed at creating a public footpath along the northeast coast of Ulster, no easy task when small farmers were reluctant to sell land or allow public access. The Ulster Coastline Appeal led the way for the National Trust’s wider Enterprise Neptune Campaign and secured the spectacular cliffs of Antrim with views across to Argyll.

Failing to persuade the NT to take on a wider selection of historic buildings in Ulster, such as the linen manufacturers’ mansions on the edge of Belfast or groups of endangered town house and vernacular buildings, he set up Hearth, a charity that provides social housing for rent in restored historic buildings, restores others for resale and has now rescued more than 100 historic buildings.

Serving on the board of the Irish Architectural Archive in Dublin, Brett was always impatient of border disputes and from the start the UAHS remit was deliberately extended to the three Ulster counties not governed from Stormont: Cavan, Monahan and Donegal.

Brett became the first chairman of the International Fund for Ireland, set up in 1986 to foster links between North and South and encourage investment in parts of Ireland that had suffered most from the Troubles. His interest naturally focused on bomb-damaged towns and he devised an ingenious scheme for sending young unemployed people to work abroad, using his contacts to set some of them to work on restoration projects in Paris.

In 1971 Brett was appointed to the board of the newly created Northern Ireland Housing Executive, serving as chairman for five years from 1979. During his time there more than 50,000 dwellings were built, to higher standards than before and with more careful attention to landscape and environment. He steered housing design away from flat roofs and little boxes to more traditional forms. For this he received a knighthood in 1990, having been appointed CBE in 1981 for his conservation work.

In 1975 Brett was invited to prepare an inventory of historic buildings in St Peter Port in Guernsey, which led to an invitation to prepare lists for Alderney and St Helier in Jersey. Like Brett’s Ulster lists these were far more substantial than equivalent official lists in England, containing not only dry descriptions of facades but also historical and archival detail and even illustrations.

Other notable volumes were an excellent Court Houses and Market Houses of the Province of Ulster and Architectural Schizophrenia. He also wrote what some consider a minor masterpiece, a slim anonymous Handbook to a Hypothetical City, by Albert Rechts (an anagram of his own name), satirising Northern Ireland and its politics. Housing a Divided Community arose from his work with the housing executive.

His more recent handsomely illustrated books on the buildings of Co Armagh, Co Antrim and north Co Down are highly observant and usable books aimed at arousing pride in local architecture. Most recently Brett had published a charming volume on English and Scottish architects in the Crimea, where he was entranced by the Alupka Palace overlooking the Black Sea — which Winston Churchill found distinctly less appealing when he stayed during the Yalta Conference. On the day Brett died friends received his latest publication, a handsome facsimile volume of 21 views of Belfast and its neighbourhood published in 1837.

Brett’s never-failing courage and determination are reflected in his attachment to the family firm’s offices in a late Georgian terrace in Chichester Road, Belfast. Though they were bombed three times he refused to move, meticulously restoring them each time. But for his efforts and leadership thousands more historic buildings in Ulster would have been demolished.

He is survived by his wife, Joyce, and three sons.

Sir Charles Brett, CBE, lawyer and champion of Northern Ireland’s built heritage, was born on October 30, 1928. He died on December 19, 2005, aged 77.