LONDON — Stephen Joyce, the gatekeeper of his grandfather James’ estate and subject of the celebrated poem “Ecce Puer,’’ has died, the president of Ireland said. He was 87.

Joyce died on Jan. 23 at his home on the Ile de Re, an island off the west coast of France, Irish President Michael Higgins said. His passing was marked in equal measure by those who admired his tenacity in securing the integrity of his grandfather’s work and those who bemoaned his lack of cooperation with scholars interested in examining the towering literary figure and his family.

His protectiveness of the family story was reflected in one of his favorite sayings: ”I am a Joyce, not a Joycean.”

“He was a doughty defender of his grandfather’s legacy and even though many of those subjected to the estate’s strictures in relation to permissions and fees actively resented them, Stephen was acting, as he saw it, to uphold his grandfather’s heritage,’’ the James Joyce Centre in Dublin said in a statement.

Joyce administered his grandfather’s estate, a job that gave him formidable power particularly until the author’s work came out of copyright. ”Ulysses,” to note but one example, is widely considered to be a masterpiece that transformed 20th-century literature.

The novel influenced countless writers, including William Faulkner, Samuel Beckett and William Burroughs. Joyceans still celebrate June 16 as ”Bloomsday,” marking the date Leopold Bloom made his famous fictional odyssey around Dublin.

“His engagement with academics, publishers, artists and institutions worldwide was often bruising,’’ Katherine McSharry deputy director of the National Library of Ireland, wrote in the Irish Times. “Over the years he refused permission to quote from or use his grandfather’s work to large numbers of creative and scholarly projects, and the stories of the unvarnished phone calls conveying his disapproval and refusal were legendary.’’

Born Feb. 15, 1932, Stephen Joyce was the son of Giorgio Joyce and American Helen Kastor. He spent his earliest years in France, though World War II prompted the family to flee to Switzerland. He studied at Phillips Andover Academy in the United States and later at Harvard.

Though he considered life as a diplomat, he ultimately became a public servant with the Organization for Economic Cooperation and Development. He married Solange Joyce in 1958 with Beckett serving as best man, McSharry said. The couple were by many accounts deeply attached and he mourned her passing several years ago.

“On our last conversations he mentioned how much he missed her,’’ Higgins said.

Ireland’s president also made a point of including the text of the poem “Ecce Puer” — literally translated from Latin as “Behold the Young Boy’’ — in his statement. The poem celebrates Stephen’s birth. It includes the following passages:

Calm in his cradle

The living lies.

May love and mercy

Unclose his eyes!

Young life is breathed

On the glass;

The world that was not

Comes to pass.