It's a book that tells the astonishing story of the books that were smuggled across the Iron curtain during and after the Second World War. Described by the Observer as a “gripping account of an intriguing and little-known Cold War moment”, "The CIA book Club – the best kept secret of the cold war" recounts the tale of how millions of books made it across the longest and most heavily guarded border on earth. In Perspective, we spoke to author Charlie English.