Take a look on the leading edge of the door at the plate where the bolt mechanism emerges. It should say there how many levers the lock contains, 2,3 or 5 being the most common. It may also carry a kitemark to BS:3621 2007 but there have been previous revisions. The frame part of the lock will have a metal box striking plate but these are not normally marked. If it is simply a metal sheet with a hole to accept the bolt, but no metal box behind, it will not be a 5 lever BS lock. To further complicate things, 5 lever only refers to the traditional lock types where the key has a long shank with a metal protusion that manipulates the levers. The other type is a cylinder lock mechanism often referred to by folks as a Yale type key. Not sure what the H&S relevance is but I'm guessing you are trying to comply with an insurers security requirements. PM me for more help if you need it. Started my insurance surveying career doing security stuff before moving on to H&S surveys.