A passport belonging to one of the Cambridge spies, a 110-year-old lemon used for invisible ink and a letter about the Queen's response to news of a Soviet agent in Buckingham Palace are among MI5 ...

A 110-year-old lemon used by a German WW1 spy to send secret messages from Britain with invisible ink is going on display in MI5’s first ever public exhibition. The blackened and flattened fruit ...

Lemon for invisible ink, spy's briefcase and IRA mortar bomb on display in unique MI5 exhibition Featuring declassified documents and objects from MI5's private collection, the exhibition marks ...