What is the ongoing terror threat to the UK?
When Jonathan Evans stepped down as the director general of MI5 in 2013, it had seemed that the terrorism threat from Al-Qaeda might be subsiding. But now just four years on - with the rise of so-called Islamic State, he conceded that Britain might only be half way through it. In his first major interview, Mr Evans discussed both the present and future terrorist threats faced by the UK. Mark Rowley, head of National Counter Terrorism Policing, explains how his organisation's ambition is to prevent any terrorist attack. (Image: Armed police; credit: Getty Images)