The regulations governing the transport of radioactive material, including the requirements for radiation hazard warning signs, are the Carriage of Dangerous Goods and Transportable Pressure Vessel Regulations 2007. Provision exists within these for radioactive materials defined as instruments of war, or components thereof, to be exempt. Notwithstanding, arrangements have been put in place for the transportation of special nuclear material that are, so far as is reasonably practicable, at least as good as those required by legislation.
Hazard warning signs are generally intended to provide information to responding emergency services in the event of an incident. The Ministry of Defence police escorting convoys have this and more information to hand. All factors, including security, will be taken into account in determining whether hazard signs will appear on the replacement vehicles when carrying special nuclear material.