Did British double agent Kim Philby murder Polish war hero General Sikorski?

General Wladyslaw Sikorski, the leader of Poland's wartime government in exile, died 65 years ago this month when his plane plunged into the sea off Gibraltar.

A British inquiry in 1943 found that the crash was caused by the plane's controls jamming. But rumours persist of a plot to kill Gen Sikorski, whose defence of the Polish national cause threatened to derail Britain's relationship with the Soviet Union.

Now Poland's president, Lech Kaczynski, and his prime minister, Donald Tusk, have demanded that Gen Sikorski's body be exhumed from its tomb in Wawel Cathedral in Krakow, the traditional burial place of Polish heroes. "The tragic circumstances of the death of General Sikorski should be explained," said the president.