Martin’s father, Alban Caroe was himself one of the great cathedral and church architects of his day, and Martin could claim equal distinction from his mother’s family, which boasted two Nobel Prize winners.

Caroe’s own greatest achievement, and the one he most liked to talk about, was the conservation of the sculpture on the west front of Wells Cathedral between 1979 and1985. After a bitter controversy, Caroe and Professor Robert Baker operated a pioneering system of stone cleaning and repair, using poultices to extract dirt, followed by consolidation with lime-water and the use of protective‘ shelter coats’ to prevent further erosion.

For much of this century, as in earlier ones, the cathedral architect was the man with all the answers. Caroe, however, took a lead by developing teams from different disciplines, including archaeologists, art historians, painting and stonework conservators. Working initially with his father, he established virtually a school of stone conservation, to which it seems today that almost every stone conservator in the country was apprenticed.

Caroe played a key role in a series of emerging professional associations, the Ecclesiastical Architects and Surveyors’ Association (of which he was president in1976), the Cathedral Architects Association and the scientifically oriented Association for the Conservation of Historic Buildings.

He also worked for the National Trust, where his greatest challenge was to mastermind the repair of Kingston Lacy in Dorset in 1982-84. His work was a model of careful, surgical repair. The architect Sir Charles Barry had cased the original brick house by Roger Pratt in stone, using iron cramps, which had badly rusted. Worse, Barry had altered the rainwater gutters so that the pipes descended inside the walls. These had started to dribble (having cracked during attempts to free them of snow and dead pigeons) and this provoked a massive infestation of dry rot.

Caroe also had to create flats for National Trust staff on upper floors, and to avoid any possibility of over flowing baths or burst pipes damaging the fine ceilings below, he devised an ingenious system of giant lead trays beneath the kitchens and bathrooms, connected to overflows on the outside of the building so that any spill or leak would be immediately noticeable.

Martin Bragg Caroe was almost born and bred to take on the care of great cathedrals, and it was a disappointment to him that despite all the work he did at Wells he was not appointed to succeed his father as architect. Instead he took charge of Rochester, where his masterly cleaning of the grimy interior was recently completed, as well as caring for St David’s and Brecon Cathedrals.

As a member of numerous ecclesiastical commissions, he knew the Church of England and its hierarchies, and could graciously marry the needs of liturgy and mission with those of history. His ability to talk was legendary, and by constant badgering he helped to ensure that care of churches in Wales was finally put on a footing similar to that in England. Through his always open door, colleagues in the office would hear him booming down the telephone, “I just want a quiet word with you”. But to some his volubility was overwhelming, and it may have been a reason why certain posts eluded him.

As consultant architect to the Tower of London (1991-98), he carried out meticulous surveys of the lead roofs and stone copings of the curtain walls, skilfully ordering the priorities of the work. He also oversaw the repair of Nos.4 and 5 Tower Green, a pair of virtually unique pre-Fire of London houses. A lesser man would have largely rebuilt them, but Caroe painstakingly grouted fissures in the brick and stabilized subsiding walls, with such care that it is hardly apparent that they have been touched.

The triumphant climax came with the cleaning, repointing and repair of the south front of the White Tower. Caroe placed stone only where essential, revealing and preserving original Norman Caen stone dressings and 17th and 18th-century replacements in Portland stone.

Caroe’s second passion in life was the family garden at Vann in Surrey to which he regularly devoted his Sundays. Laid out by Jekyll, it was probably almost equally the work of Caroe’s grandfather, who largely created the fine house, which Caroe so loved, organically extending the Surrey vernacular with the same skill as Lutyens.

!n 1962 Caroe married Mary, daughter of the naval historian Captain Stephen Roskill, and she survives him, together with his second son and three daughters.