CEP Senior Advisor Ian Acheson writes: "I know a bit about the threat management of violent extremists. In 2015 Michael Gove, who was then justice secretary, asked me to conduct an independent review of Islamist extremism in the prisons and probation system in England and Wales. What we found was so shockingly bad that I had to agree to the language in the original report being toned down. With hindsight, I’m not sure that was the right decision."