Home Secretary Theresa May told the Conservative Party conference: "We should not for one second underestimate the threat we face from terrorism and the challenges we must meet in confronting extremism."
"Whatever the race, religion and beliefs of a terrorist, whatever the race, religion and beliefs of their victims, this is Britain.
"We are all British. We stand united against terrorism and we will never succumb to violence."
More top news
The book by Cameron comms chief Sir Craig Oliver reveals that Mr Cameron was frustrated with Theresa May's neutrality during referendum.
Cloud and outbreaks of rain will ease away eastwards during the morning, clearing the east coast around midday with sunny spells developing.
Police and emergency services are attending the scene.