Booker Prize winner Richard Flanagan adds Baillie Gifford nonfiction prize to his trophy shelf

LONDON — Australian writer Richard Flanagan completed an unprecedented literary double on Tuesday, winning Britain's leading nonfiction book prize a decade after being awarded the Booker Prize for fiction.

Flanagan was awarded the 50,000 pound ($63,000) Baillie Gifford Prize for his genre-bending memoir ''Question 7,'' which combines autobiography, family history and the story of the development of the atomic bomb.

Flanagan won the Booker Prize in 2014 for ''The Narrow Road to the Deep North,'' a novel that drew on his father's experiences as a World War II prisoner of the Japanese military.

Baillie Gifford Prize director Toby Mundy said that for the same writer to win the leading U.K.-based fiction and nonfiction awards was ''completely unprecedented.''

Journalist Isabel Hilton, who chaired the judging panel, said Flanagan had written a ''meditative symphony of a book'' that weaves together ''enormous traumatic events of the 20th century … with an extraordinary personal narrative.''

Hilton said Flanagan's fiction background was evident in the book's inventiveness and ''narrative beat.''

''I think the book benefitted from that novelist's eye,'' she said.

In a recorded message, Flanagan called the threat from climate change existential, and said he wouldn't accept the prize money unless the finance firm that sponsors the prize draws up a plan to end its investments in fossil fuel companies.

Edinburgh-based Baillie Gifford has faced protests from environmental groups over its investments in fossil fuel businesses and firms linked to Israel's defense sector. Amid the controversy, the company stopped sponsoring several British book festivals, including one of the lagrest, the Edinburgh International Book Festival.

That has prompted a backlash from others in the culture world, who say it starves the arts of much-needed funding.

Baillie Gifford partner Peter Singlehurst criticized the campaigners' demands, saying ''purity is illusory.''

''What is being demanded is something we cannot do,'' he told attendees at the ceremony. ''The literary community must either accept us as they find us, or not at all.''

''They've been exemplary sponsors and I think exemplary supporters of the literary culture of this country,'' he said.

Flanagan's book beat five other finalists, including American writer Annie Jacobsen's sobering ''Nuclear War: A Scenario'' and Pulitzer Prize winner Viet Thanh Nguyen's autobiographical ''A Man of Two Faces: A Memoir, A History, A Memorial.''

Founded in 1999, the Baillie Gifford Prize recognizes English-language books in current affairs, history, politics, science, sport, travel, biography, autobiography and the arts. It has been credited with bringing an eclectic slate of fact-based books to a wider audience.