SERVING officers experimented with using semen as an invisible ink to write top-secret letters during the World War I, according to Keith Jeffery’s book.

MI6 HAS lifted somewhat the veil of secrecy that has surrounded its operations for the past century with the publication of the first authorised history of the service.

PRESIDENT Mary McAleese will attend a major conference in Cork at the weekend to mark the 90th anniversary of the 1916 Rising.