The point of a war is to win. This is an elective war, so the outcome isn't as dire for the aggressors as for the subjects of the war. Still, there isn't any point in giving the home team (read insurgents) any advantage at all. Consider:
If Harry shoots a teenager, it's propaganda gold.
If Harry goes out on patrol with his crew, every insurgent for 200 miles will know about it and the crew (with Harry) will be targeted. And shot at. With considerably more enthusiasm than the usual bunch of recruits from nowhere in particular. Should any of the crew be hit because Harry was nearby, then prop gold. If they tag Harry, PLATINUM! but one of his grunts? Still PG. It will run in OUR papers that some schmuck, from some place in Wales that god couldn't pronounce, got whacked, because of Harry.
The list of negative possibilities goes on. It's WRONG to subject your people to unnecessary hazard for PR reasons. The English officers are behaving properly. Presumably, given Sandhurst and his background, Harry will take orders and do it right as well.
You are being seriously overly simplistic. And because you're being a twit, I don't see a clear opportunity to needle Peter for being English.. (*)
(*) Yes, CRC, there are only 2 dots in the ellipsis...