I think pretty much every single UK insurer excludes terrorism-related incidents from coverage. Some of them got hit quite hard by claims after the Bishopsgate and Canary Wharf bombs (1996?). If you want terrorism risks to be covered on a policy you generally have to take out separate insurance and pay a fairly hefty premium. I live close to a major railway station and I know that the development I live in has paid to take out this extra cover in addition to standard buildings and contents insurance.