"It is right that we are suspending campaigning activity in this referendum and everyone's thoughts will be with Jo's family and her constituents at this terrible time," he said in Gibraltar where he had been planning to deliver a speech.

What's notable is that he didn't say they were suspending the campaign 'today' or when it would resume. That's helped to feed rumours that the vote will be delayed.

Update: The 'remain' campaign now says that activities will remain suspended on Friday.

The Telegraph already has a full profile on the assassin, who's name is Thomas Mair.

A screen capture of video from his arrest

"I don't think he belonged to any political party and I never heard him express any views about Europe or anything like that," a neighbour said.

There is some signs that he had mental health problems because he spoke to the Huddersfield Daily Examiner in 2010 about volunteering at a local park and said, "I can honestly say it has done me more good than all the psychotherapy and medication in the world."