'HR staff', 'head office'????
Are the Armed Forces turning into a large poorly run civvy corporation now??
No,
Head Office is the way to refer to Main Building when talking about its role as a Department of State. If you wanted to refer to the same place but in its role as the most senior military headquarters in the UK, you'd use
MOD HQ.
So to answer your question, it isn't a large, poorly run civvy corporation. It's a large, poorly run Government Department.
