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Finding the real King's Speech

4 January 2011 Last updated at 20:29 GMT

The King's Speech, which tells the true story of King George VI's attempt to overcome his stammer with the help of maverick Australian speech therapist, Lionel Logue, is due for release on Friday.

The film is already tipped for Oscar glory, but such success might not have been possible without the discovery of Lionel Logue's diaries only nine weeks before filming began.

Will Gompertz spoke to Lionel Logue's grandson Mark about the unearthed archive and what it reveals about the remarkable friendship between the King and his therapist.