Dr Julian Lewis: Can I follow the logic a little further about what is necessary to keep British society safe? I am sure that people on both sides of the House believe that the best way to deal with something such as this would be for each country to take people back, put them through the court process, prosecute them and, if necessary, imprison them. The problem is: what do we do when we do not have an offence for which a person can be prosecuted? We now have a new offence of entering a designated area. What is the maximum prison sentence that someone would serve if convicted of that offence? If it is a very short period, will the Home Secretary consider upgrading the law on treason – as was done temporarily during the second world war – to ensure that anyone who comes back will serve a very long sentence? It takes between 20 and 25 security service operatives to cover a single suspect 24/7, and that is simply impossible when there are hundreds of such suspects.

[The Secretary of State for the Home Department (Sajid Javid): My right hon. Friend has made a number of good points. He is, of course, absolutely right: someone who returns can be prosecuted for an offence only if the relevant laws exist. He alluded to new counter-terrorism ​legislation that is included in the Counter-Terrorism and Border Security Act 2019, and to the “designated areas” offence. I believe that the maximum sentence that can be received for that offence is up to 10 years. It was precisely to try to secure more tools with which to prosecute returning fighters that I made that amendment to that Bill. We are constantly considering what further improvements can be made, and what further tools can be introduced to prosecute returning foreign fighters. I agree with my right hon. Friend that it is time to look at the laws on treason, and to modernise them.]