A military Clerk of Works is quite a different beast to the one what Stainmaster described. Whilst acting as he described is part of the job, it's a small portion of the job.
The bulk of design work for work to be carried out by Military Construction Forces (i.e. Royal Engineers) and the major of concept design work that's contracted out on overseas operations is produced by Clerk of Works and Military Plant Foremen. The professionally qualified engineer officers sign off the designs as complying with the relevant regulations. They only tend to get involved in complex design which is beyond what Clk Wks get taught.
Whilst most RE SNCOs go on the site safety supervisor (or whatever it's called nowadays) course, there is an expectation that a lot of the health and safety stuff on sites goes to them, because of their more in depth knowledge. This includes Authorised Person duties including (but not limited to) confined spaces, working at height, HV electric, LV electric, petroleum, medical gases, airfield ground lighting and boilers/pressure vessels.
There are Clk Wks embedded within Defence Infrastructure Organisation across the globe and within the UK airfield main operating bases, overseeing the infrastructure support contracts, both within the facilities management and works delivery teams.