The UK's terrorism threat level has been downgraded from "severe" to "substantial", the Home Office has said.

Priti Patel, the Home Secretary, said the level meant the UK remained at "a high level of threat" and an attack "might well occur without further warning".

It is the first time since August 2014 the terrorism threat has been this low. Substantial is the third of five ratings at which the threat level can stand.