Centre for the Protection of National Infrastructure: This publication offers security advice and good practice for any organisation looking to protect against the risk of a terrorist act or limit the damage such an incident could cause. It sets out how a security plan might be developed and updated, the key measures that can help protect staff, property and information and how businesses can prepare for the worst.

http://www.cpni.gov.uk/Docs/protecting-against-terrorism-3rd-edition.pdf

-Urs