Margaret Thatcher's story makes Samuel Johnson Prize list
Six titles, including books about bees and a former prime minister, are on the shortlist for the Samuel Johnson Prize.
Margaret Thatcher: The Authorized Biography, Volume One: Not for Turning has been written by Charles Moore.
Also making the list are Empires of the Dead by David Crane; Return of a King by William Dalrymple and The Pike by Lucy Hughes-Hallett.
Under Another Sky by Charlotte Higgins and Dave Goulson's A Sting In The Tale complete the non-fiction prize lineup.
Martin Rees, chair of the judges, said the books "are very different, but each has enlightened and entertained the judges".
He added: "These finely written, highly accessible and stimulating books all deserve a wide readership."
Rees led a judging panel which included historians Mary Beard and Peter Hennessy; director of Liberty Shami Chakrabarti; and writer and reviewer James McConnachie.
The judges said that In Under Another Sky, author and Guardian journalist Charlotte Higgins "reaches into Britain's past and brings the Romans vividly back to life".
Empires of the Dead: How One Man's Vision Led to the Creation of WW1's War Graves was described by judges as "a stand-out title amongst the dozens due to be published on the Great War in the next few months".
The Pike, a biography of poet Gabriele D'Annunzio, was, remarked the judges, "a superb example of biographical writing at its finest, demonstrating how one man can alter the course of history".
Conservationist Dave Goulson, long obsessed with wildlife, details the mysterious ways of the bumblebee in A Sting In The Tale, "a book that will do much to improve our appreciation of these fascinating insects and their importance to our ecosystems," said the judges.
Charles Moore's book, handpicked as he was to write Margaret Thatcher's biography was "a very fair and thorough chronicle" of the late former PM, while William Dalrymple's Return of a King - an analysis of the First Afghan War - was "as fine an example of unlearned lessons from history as you could find".
The shortlisted authors will appear at Cheltenham Literature Festival on 6 October and the Southbank Centre on 3 November.
The BBC Culture Show will also broadcast pieces about each work on 30 October on BBC Two.
This year's winner of the £20,000 prize will be announced on 4 November.
Last year's winner was Wade Davis's book Into the Silence: The Great War, Mallory and the Conquest of Everest, about explorer George Mallory's attempt to conquer Everest.