David Davis has been a candidate for the leadership of the British Conservative party but he has also made a name for himself as a civil liberties campaigner - arguing against what is sometimes called the 'surveillance state'. So what does he make of the massive collection of data by the US National Security Agency and Britain’s GCHQ revealed by the American whistle-blower, Edward Snowden? In the years since the 9/11 attacks - have we got the balance wrong between liberty and security?(Image: David Davis, Conservative MP at the 2005 Conservative Party Conference in Blackpool. Credit: Associated Press)