The UK has always adopted a policing-led intelligence response to terrorism in this country. But the advent of jihadist terrorism has posed new challenges, which continue to evolve. UK intelligence services now collaborate at far deeper and integrated levels than was ever previously the case, both domestically and in relation to international partners. They are also more effectively coordinated at the centre than ever before, through the Office of Security and Counter-Terrorism, the Joint Terrorism Analysis Centre, the Joint Intelligence Committee, and the National Security Council. In this respect, the UK compares very well with many of its partner countries. New challenges, however, continue to proliferate. The modalities of jihadist terrorism look for novel ways of mounting attacks, so more communication and planning techniques have to be monitored. And the internet goes progressively ‘dark’ for the agencies as end to end encryption and the changing business models of the internet giants have the effect of freezing the access of the agencies to important areas for intelligence purposes. There is consensus among intelligence professionals that the agencies work far better than used to be the case, but probably not well enough to meet the way future challenges seem to be evolving. Most worry about the future effectiveness of international collaboration.