I have a group of post-nominals, all either academic or professional (Member of professional body, Chartered etc). The academic ones stay with me for life, the professional ones will lapse when I retire. They are only very occasionally used when my employer wants to put details on a tender or similar to show prospective customers we know what we are talking about. I don't think I have ever used them otherwise. But if I had an Award or Order, I'd probably use it (But that's never going to happen now!).
A friend who has a Military MBE uses that but none of his other (many) qualifications. Another who has a PhD doesn't even use 'Doctor', as, to quote him, 'A history Doctorate is no relevance to my current job'
The Chief Constable is curious, as to get to that rank he must have considerable leadership qualities - I suspect he's embellished his CV when young but been caught in that lie for the rest of his career