Engagement cards detailing Churchill's activities are among items to be sold
A large private collection of Sir Winston Churchill memorabilia is expected to raise about £1m when the first part of it is sold next month.
Auction house Christie's said the material, which includes diary entries, letters and an unsmoked cigar, provided a "fascinating insight" into his life.
The former prime minister's belongings were amassed by Malcolm S Forbes Jr over more than 30 years.
The collection will be sold in three parts, the first in London on 2 June.
The first sale, of about 150 lots, is forecast to fetch about £1m.
The second will take place in New York on 3 December and the third sale, in London, is expected to be held in summer 2011.
The star lot is likely to be the former prime minister's engagement diary, which provides a source of information for his daily activities.
The 30 engagement cards give daily details of his appointments from September 1939 to June 1945 and are expected to realise between £80,000 and £120,000.
The diary was kept by his private secretaries and recorded summits with leaders such as Roosevelt and Stalin, as well as his regular Tuesday meeting with the king and leisurely pursuits including a football match and occasional theatre trips.
The auction will also offer the wartime prime minister's account of the Battle of Omdurman, which he took part in as a young soldier, in a letter which is estimated at between £30,000 to £50,000.
In the letter, written in September 1898, he described encountering the enemy and being shot at as "the most dangerous two minutes I should live to see".
"Winston Churchill is one of the most famous historical figures of the 20th Century and his feats as a politician, and as the wartime prime minister of Great Britain in particular, continue to attract great attention and admiration," said Thomas Venning, director of books and manuscripts at Christie's, London.
He said the "outstanding collection" presents an "exceptional and fascinating insight" into Churchill's "personality, character, sharp wit" and "distinctive way with words".
Malcolm S Forbes Jr, who gathered the collection, is chief executive of Forbes Inc and the grandson of Forbes magazine founder BC Forbes.