What the Brits would be doing about now is arming the Kurds and sending them to police the Sunni Triangle. The Kurds have already asked us to let them do it. They're begging for the chance to get a little payback. They said, "We guarantee we'll have the place pacified in a week. We can read these people! You can't! We can tell who's a guerrilla and who isn't! All we need is a few fingernail-pulling pliers and a portable generator hooked up to a cattle prod or two!"
Of course we won't let them, because it'd be messy, like Sabra-Shattila times ten. There'd be dead Sunnis thicker than sagebrush. But the Brits'd do it, and it'd work. Then, when the Kurds had bled the Sunnis out, they'd recruit a new police force, all Sunni and all-volunteer, to go police Kurdistan, bleed the Kurds for a while so they don't get too strong.
That's the sort of thing you have to do if you want to run an empire. But you guys, you're just brave enough to get us into trouble and not brave enough to see it through. You want to kick ass, plant the flag on somebody else's land and blow stuff up, and then have everybody on the ground love you for it.
That's not an empire. That's a bedtime story for pussies.