Secret of Churchill's diary revealed

The wartime diary of Winston Churchill was the subject of a bizarre legal tussle involving the government and the historian David Irving, records reveal.

The newly released files document an extraordinary exchange, sparked by the former prime minister's grandson. In 1979, Winston S Churchill, who died in 2010, wrote to the Cabinet to express concern that the diary had fallen into Mr Irving's hands. In the same letter he accused spies Anthony Blunt and Kim Philby of involvement in the death of Poland's wartime leader, General Wladyslaw Sikorski, in a plane crash in 1943.

The Cabinet Office correspondence, marked "secret", was contained in one of the thousands of files released under the 30-year rule by the National Archives.

Last night Mr Irving said he had initially been quoted £250,000 for the diary, which was eventually returned to the National Archives.