Remarkable problem, but not hard to solve.
Start a forced muslim assimilation program.
Force a rejection of Sharia and a oath to the Crown.
No compliance is immediate expulsion.
That should clear out 50%.
Any muslim engaged in social media threats - midnight raid and blindfolded ride to somewhere in the middle east.
Any muslim terrorist and all accomplices including those who said nothing - wood chipper in public square.
program program where all muslims are identified and forced through an
At one time the Brits got a lot of mileage out of public executions in pig pens.