How strong is right-wing extremism in the UK?

After the murder of MP Jo Cox by an extreme right wing fanatic, Professor Matthew Goodwin explains that the far-right in the UK is a fragmented and unpredictable group.

An expert on right wing extremism, Professor Goodwin tells BBC Radio 4's PM programme he expects there will be greater debate about what drives this kind of violence, and the difficulty the security services have in tracking it.