Krystyna Skarbek was travelling outside of Poland when the country fell to the Nazis. In order to fight back after the occupation she threw her lot in with British intelligence offering her unique courage and skills to courier early reports back of the Nazi plan - Operation Barbarossa. Skarbek would go on to serve in three theatres of war and became one of the highest trained and most effective of British spies. 

Clare Mulley, the author of A Spy Who Loved, tells us a short part of Skarbek's remarkable story.