Plymouth Herald published UK terror threat level raised to critical: What it means and why

Theresa May has said the threat level of a terrorist attack was being raised to its highest possible rating this evening in the wake of the atrocity in Manchester last night.In a live televised statement from Downing Street, the Prime Minister said the terror threat level would be increased to "critical", meaning an attack was expected imminently as it was possible a "wider group of individuals" could have been involved in the Manchester Arena attack rather than just suicide...