Ian Bryce specialised in castles and proved to

be one of Scotland's most noted architectural histo-rians. He wrote extensively on the subject over the past 45 years.

Born and raised in Aberdeen, he was a toonser and proud of it, great-grandson of a city brassfounder. However, his many callings did not include involvement in the family business, something of a surprise given all the different aspects of his life - marine engineer, taxi driver, Doric scholar, poet, literateur, Burns enthusiast, politician, heraldist, and writer.

Ian, the lifelong nationalist, was perhaps an unlikely person to be a politician. Harangue and intrigue were not his bread and butter. Yet in 1974, he became area organiser for the Scottish National Party. The word ''area'' surely stretched even his noted sense of humour, for his parish stretched from high-water-mark on the Tay to the lighthouse at Muckle Flugga.

Nobody knew he was a heraldist, not until the Heraldry Society of Scotland arrived at the Wine Tower in Fraserburgh one day, with Ian as guide. He completed his architectural exposition, then, without changing gear, launched into an interpretation of the heraldry in that authoritative but self-effacing style of his. His wisdom now forms the standard heraldic text on the Wine Tower.

As a lecturer, he scorned notes. He'd stand on the floor and entertainingly expound fact after fact in his precise diction. That he was actually a wee man, who barely scraped 5ft 4ins, was irrelevant, for his personality filled the room. Ian quartered north-east Scotland, delivering lectures and talks. He never asked a fee, and, human nature being what it is, was rarely offered one.

He carefully catalogued his output for the 45 years from 1956 to March this year, and it runs to 25 pages of close type, covering an enormous range of style and subject matter: lectures, talks, monographs, broadcasts, books, poetry, videos, reviews, essays, and cartoons - an output all the more remarkable for someone in full-time employment. Ian's intellect guaranteed to the editors who published him that he was a heavyweight whose material they were fortunate to have.

Ian the writer contributed to a dozen periodicals over his life, but is ever associated with Leopard magazine, a monthly of general interest circulating in north-east Scotland. Always first to put a shoulder to the wheel, he wrote for Leopard from the start.

In those pioneering days, a quarter of a century ago, he worked under a hard taskmaster, for the assistant editor was his wife Irene.

Leopard launched Ian the castles' expert to a wider public. His ''Castle of the Month'' feature proved an instant success. Month after month, Ian patiently drew out the threads of the

stories of more than 50 castles in Aberdeenshire, Banffshire,

Kincardineshire, and Moray. His audience loved him for it.

His interest started one holiday with his parents at Premnay, Aberdeenshire, when he cycled to nearby Leslie Castle, then a ruin. He was just 11 years old. By his early teens, he had devoured MacGibbon and Ross's magnum opus. As

a young man, he never missed Dr W Douglas Simpson's weekly lectures at the university.

Ian's knowledge of castles was fearsomely encyclopaedic and based entirely on original research, nor did he confine himself to north-east Scotland. A friend of his recalls: ''Leitholm Peel is a rickle o' steens in a corner of a Berwickshire park, a pocket handkerchief of a ruin whose mark on Scotland's history is near enough zero. Casual mention of Leitholm to Ian produced, by return, three pages of erudite Bryciana.''

His death from cancer robs historians of his work on the hypothesis that North-east Scotland and Galloway communicated to each other a shared tradition in types and purpose of castellated architecture. That the north-east glories of Crathes and Craigievar could be reflected equally well in, say, the Galloway structures of Carsluith or Cardoness.

Ian the communicator was discursive, discoursive, and discussive, someone who shunned debate for the persuasive enjoyment of stimulating company in seeking after truth. While not afraid to express his views, he never forced them on anyone. He wore his learning lightly, and neither sought nor courted recognition.

Across the social spectrum, he was respected for scholarship, wit, and courtesy, and valued for his friendship. To his many friends he was a man who cheerfully gave, and never once asked for anything in return.

He is survived by Irene, his wife of 37 years, son Robert, and granddaughter Judith.

Ian Boice Duncan Bryce; born Aberdeen December 7, 1935, died Aberdeen June 22, 2001