Ex-MI5 boss: UK faces Islamist threat for decades

The UK may continue to face the threat of Islamist terrorism for another "20 to 30 years", the former head of MI5 has said.

Lord Evans told the Today programme the "emergence of IS" had meant the terrorist threat had changed.

"I think we are going to be facing 20 or 30 years of terrorist threats and therefore we need absolutely critically to persevere," he said.