There has been a huge increase in the threat of terrorism in Europe following the Charlie Hebdo shootings in Paris, the related hostage-taking in a kosher supermarket at Porte de Vincennes in east Paris and the November 13 attacks in which 130 were killed and hundreds injured in a series of shootings and suicide bombs.
Rowley said the threat had moved on from simply Daesh encouraging jihadist terrorists to attack police and military or government targets. Now the threat was to "western lifestyles."
"Terrorists groups are always about impact. Terrorists groups have always wanted to do a grander and more spectacular attack because they have more impact. In recent months we've seen a broadening of that, much more plans to attack western lifestyle," Rowley said.
"Going from that narrow focus on police and military as symbols of the state to something much broader. And you see a terrorist group which has big ambitions for enormous and spectacular attacks, not just the types that we've seen foiled to date."
'Run, Hide and Tell'
Police in the UK have released a new video, following the November 13 terror attacks in Paris, advising Brits to "run, hide and tell" if they hear gunshots, in a further sign of nervousness about a similar attack in the UK.
130 people died and hundreds more were injured, in a series of attacks in which radicalized Islamic terrorists either detonated suicide bombs or opened fire indiscriminately in cafés, restaurants and — with the highest fatalities — the Bataclan music venue in Paris.
In a clear response to the attack, and an acknowledgement that a similar attack could take place anywhere in the UK, the National Police Chiefs' Council has released a five-minute video giving advice on what the public should do in a similar attack.
After the sound of a series of gunshots, a voiceover says: "If you hear gunshots, the best option is to evacuate, but only do so if it won't put you in greater danger. First, consider your route. Act quickly and quietly, leaving your belongings behind. Insist others come with you, but don't let their indecision slow you down.
"Once you have identified a safe route, run. Consider your route as you leave. Will it place you in the line of fire? Is it safer to wait for the attacker to move away before you continue? If you can't move to safety, hide," the voiceover says.