During his seven years as head of MI5, Andrew Parker has dealt with Islamist terror plots, Russian and Chinese espionage and the rise of far-right white extremism. 

But the biggest challenge, he said, is technology and how it is transforming how the UK Security Service operates. This will require a top-to-bottom examination of MI5’s structures, its relationship with the private sector and a shift to targeted monitoring of terror suspects “in real time”. 

In an interview with the Financial Times, Sir Andrew — who is stepping down as director-general of MI5 in April — suggested his agency would have to form partnerships with retailers, banks and internet companies to access information about the 3,000 people it has under close investigation at any one time.