By Martin Robinson PUBLISHED: 07:33 EST, 4 January 2013 | UPDATED: 11:27 EST, 4 January 2013 He was Queen Elizabeth's I's spymaster, protector and the deeply-Protestant man bent on crushing all those who supported the Pope in Rome. But 500 years on it appears a cunning plot by a subversive Catholic artist may have been uncovered - because below a priceless portrait of Sir Francis Walsingham lies a secret image of the Virgin Mary holding a baby Christ. The painting, which may also contain a sketch of Joseph or an angel, is from the 1580s and created at the height of Walsingham's powers, while he served as the Tudor queen's lord treasurer and secretary.
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Sir Francis Walsingham led queen's defence against threat from Rome
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Hundreds of suspected Catholics were burned or hanged at his hand
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He also uncovered plot to put Mary Queen of Scots on the throne
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An 1580s painting x-rayed shows image of Mary and Christ under his face
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Portrait of poet Thomas Sackville also contains hidden glimpse of Jesus
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Anti-Protestant discoveries made by National Portrait Gallery in London
'The @placeholder are the absolute enemy at this period so the idea that you’ve got this wonderful devotional image underneath your portrait would probably be rather horrifying to him.