You will need this permit if you work for a security firm and have been nominated by the licence holder to sign firearms in and out to armed security guards. This permit does not authorise the use or acquisition of firearms. If you hold a category H firearms licence (security guard) then you do not require this permit.
All firearms are kept on a register, they are signed out to armed security guards at the start of each period of duty, and then signed in at the end of each period of duty. This is to ensure the safe keep of all firearms.