The Knight of Glin, Mr Desmond Fitzgerald, has donated his family papers to the University of Limerick. The papers, in 120 manuscript boxes, contain personal letters, diaries and documentation relating to financial transactions and rental accounts since the 19th century.
The knights of Glin are a west Limerick Geraldine family which traces their origins in the area back to the 13th century. Part of the castle, now a guesthouse on a 500-acre demesne, is being restored.
"They have been there since 1220. They were Gaelicised. They were not considered to be a British planter. The locals had a different attitude towards them until the Land Wars," said Mr Fitzgerald, the 29th bearer of the hereditary title and president of the Irish Georgian Society. He has been Irish agent for Christie, Manson & Woods since 1975.
He said the family's history was one of survival although they had bankrupted themselves in the building of their castle in the 18th century. "They were on the wrong side in the Jacobite wars and the Cromwellian wars. They were Catholics during the Penal Laws. They were able to survive mainly because they became Protestants in the 18th century."
The papers would be of regional historical interest and contained cheque stubs, invoices, conveyances and more than 1,000 letters received by his late mother, Veronica Fitzgerald, who was a cousin of Winston Churchill.
Ms Lisa Collins, an archivist, who spent a year cataloguing and cleaning, said the letters, from friends, artists and musicians, gave a distinctive impression of 20th-century life. "They are a real resource. They are full of information."
The papers were formally presented to the Special Collections section of UL's Glucksman Library this week. Mr John Lancaster, its director, said they were an important addition to the relatively new library.