Desmond FitzGerald, the 29th Knight of Glin, who died on Thursday at the age of 74, was a scholar of international renown and a familiar figure in Dublin.
Although Glin Castle on the Limerick/Kerry border was his main residence, he kept a house in the city as a base for his work with the Irish Georgian Society, of which he was president, and as the London auction house Christie's representative in Ireland.
Over the years I met him frequently at receptions and gallery openings and found him a charming if somewhat reserved man, but always endlessly helpful when asked about matters concerning Irish art and architectural history.
His title, the Knight of Glin, also known as the Black Knight, was one of three Anglo-Irish hereditary knighthoods that have existed in Ireland since feudal times and have been held by members of the FitzGerald family who arrived in Ireland with Strongbow.
The other two are the Knight of Kerry, or Green Knight, and the White Knight, a title now dormant. The current Green Knight is ex-British MP Sir Adrian FitzGerald, a former mayor of London.
Because his title was an ancient Irish one, Desmond FitzGerald was not formally addressed as Sir Desmond, but simply as 'Knight'. As something of a stickler for manners, he liked being addressed in this way.
Only his closest friends dared call him by his nickname 'Knighty', in much the same way as his relative, the late Thady Quin, Lord Dunraven, was known as 'Lordy' in Adare.
As Desmond FitzGerald has left no male heir, his title is now likely also to become dormant.
Desmond FitzGerald's branch of the family from very early on married into the Gaelic Chieftain class and remained staunchly Catholic until quite some time after the Penal Laws were introduced.
One of Desmond FitzGerald's ancestors supported Hugh O'Neill at Kinsale, another died at the Siege of Derry fighting for James II and yet another joined the United Irishmen.
The Knights of Glin have sometimes been quite a colourful lot.
In 1600, when Glin Castle was being besieged by Elizabethan forces, the then knight's six-year-old son was captured. The besieging general tied the boy to a cannon muzzle and threatened to blow him to pieces if the knight did not surrender. The Black Knight replied that he was virile, his wife strong and it would not be difficult to produce another heir.
A more recent ancestor, the 25th knight, John Fraunceis Eyre, better known as 'Cracked Knight' or 'Cracked Jack', had a habit of riding his horse into the homes of those he was visiting.
Desmond, the 29th knight, was the youngest of three children, and the only boy. Brought up in Glin Castle, he and his older sisters were basically raised by nannies and governesses. His parents' marriage was deeply unhappy, and Desmond and his sisters Rachel and Fiola rarely saw them.
At the age of eight he was sent to school in England, which he has always said he enjoyed thoroughly. His father, who suffered from TB and spent much of his time at sanatoriums in Switzerland, died when he was 12.
His mother subsequently married a Canadian millionaire who encouraged his long-held and developing interest in art history and architecture, which he studied at the University of British Columbia and then followed up with an MA at Harvard.
Armed with his degrees he moved to London and got a job as curator of the furniture department of the Victoria and Albert Museum.
He married twice. His first marriage, to the glamorous fashionista LouLou de la Falaise who later became the muse, confidante and creative partner of fashion designer Yves St Laurent, was short-lived.
He has described that union as "a youthful escapade", and when he was 29 he married Olda Willes, who had been a great friend of LouLou. They had three children, Catherine and Nesta, who were born in London, and Honor who was born in Ireland, as the family had moved back to Glin Castle by then. It was inevitable he would return, as there had been a FitzGerald living in the house for almost 800 years.
Although his Canadian stepfather had spent a lot of money maintaining the fabric of Glin Castle, he and Olda set about refurbishing the house, scouring Irish and London auction houses for choice period furniture, paintings and books.
In 2009, the castle, with its 15 bedrooms and 500-acre demesne, was opened as a luxury hotel between March and November, catering for small groups of upmarket visitors. It has huge appeal to Americans, many of whom would have been familiar with the knight through his Irish Georgian Society fundraising work there.
That same year the knight consigned almost 200 lots of his collection of period furniture and art to Christie's in London. It was a wrenching decision prompted by the necessity to secure the future of Glin Castle. To his delight, the sale made just over €2m, almost twice the pre-auction estimate.
Some years ago in an interview with Aengus Fanning, the editor of the Sunday Independent, Desmond FitzGerald quoted one of his relatives on his mother's side, Winston Churchill, as once remarking: "You make a living by what you get, you make a life by what you give."
As a highly regarded art historian and writer with a lifelong commitment to conservation issues, the 29th Black Knight led a public life that has made a valuable and lasting impact on the preservation of Ireland's architectural heritage.
Desmond John Villiers FitzGerald, 29th Knight of Glin (13 July 1937-14 September 2011). He is survived by his wife Madam Olda FitzGerald, née Willes, and three daughters, Catherine, Nesta and Honor