Green Party policy states ‘it should not be a crime simply to belong to an organisation or have sympathy with its aims, though it should be a crime to aid and abet criminal acts or deliberately fund such acts’. 

On BBC1’s Sunday Politics Miss Bennett was challenged about the policy and whether that would make it legal for people living in Britain to join brutal terrorist groups such as ISIS.

She said: ‘This is a part of our policy that I think dates back to the age of the ANC and apartheid South Africa.’

Pressed on whether that meant it would be allowed to be a member of Al Qaeda or IS, she said: ‘Exactly. What we want to do is make sure we are not punishing people for what they think or what they believe.