How does a bodyguard who failed so miserably in protecting Princess Diana, suddenly become a security expert?

That's a very good question.

As far as hat color, maybe he's neither. Was he even supposed to survive the accident? Perhaps he was approached afterwards and told, if he values his life, he'll have amnesia? And thus, was rewarded for the memory lapse.

That's a lot of years of infiltration with no whistleblowing, so who knows. I'm not sure anybody ever will (know).