The Brits are, as usual, blaming themselves. The US, with its "intolerant" policies, has actually not been that much more successful in discouraging Muslim killers; we have just been more successful in catching them before they do any real damage. But our Muslim inhabitants, including native and foreign born and converts, have certainly been trying.
It's probably going to take a few more attacks for Britain to learn the only history lesson worth learning: Islam is a cult built on violent conquest, and there is no way of dealing with it other than opposing it head-on and defeating it.
Muslims make good citizens of non-Muslim countries only when they think Islam is powerless to conquer those countries. But even then they don't stop trying. Some Muslims, mostly poor laborers and farmers, had been permitted to stay in Spain after the expulsion of the Jews and Muslims in 1492, but in about 50 years, they were all deported - after having wiped out some Christian villages on the Mediterranean coast, torturing the priests to death, and then being caught receiving weapons smuggled in from Muslims in the Middle East.