Joining al Qaeda or ISIS should not be illegal, the leader of the Green Party has said. She could see no conflict between that and her party’s wish to downgrade much of Britain’s military. The party plans to turn a number of British military bases into nature reserves, convert military engineering firms over to manufacturing renewable energy technologies, and scrap the nuclear weapon deterrent.

Speaking to Andrew Neil on today’s Sunday Politics, Natalie Bennett, leader of the Green Party confirmed that the Green Party’s policy document states that “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.”

“This is a part of our policy that I think dates back to the age of the ANC and apartheid South Africa,” she said.

When quizzed on whether that meant people would be allowed to be members of al Qaeda or ISIS, she replied “Exactly. What we want to do is make sure we are not punishing people for what they think or what they believe.

“Obviously actions of inciting violence, supporting violence, those are absolutely unacceptable, illegal and should be pursued to the full extent of the law. What we are talking about is a principle that you shouldn’t be punished for what you think. And we need to balance, we do not protect freedom by destroying it.”

However, the policy document also states “the Green Party is committed to the early conversion of economic, scientific and technological resources presently used to support the arms race, to socially useful and productive ends. Some military training areas should be decommissioned and used as nature reserves, with suitable provision for access by the public.

“An imaginative programme of arms conversion could use many of the skills and resources at present tied up in military industry, to create new jobs and produce socially useful products. […] New renewable energy industries, for instance, could be set up in the same area and use the same skills and resources as the existing arms industries e.g. wave power (shipbuilding), wind power (aerospace) and tidal power (power engineering).”

“We obviously need to be able to defend our own borders, civil defence, and we have a real responsibility as a rich country to contribute to UN peacekeeping forces,” Ms Bennett said, but she was unwilling to put a figure on how many military personel might be cut.

On Thursday, Foreign Secretary Philip Hammond warned tht Britain is at “very significant risk” of from a terror attack committed by ISIS (otherwise known as ISIL). “We have to regard ISIL as probably the greatest single immediate threat to Britain’s national security at the moment,” he said.

“There’s a very significant risk of an ISIL-inspired attack being planned and, if we are not successful in intercepting it, executed by ISIL sympathisers who live in the UK but are inspired by what is going on in Iraq and Syria.

“We know there are people out there who wish us harm and we have to be vigilant and we have to work extremely hard to make sure we identify and disrupt these plots before they come to the stage of an attack.”

The two policies are not the only contradictions contained within the Green Party’s policy book. They also want to bring in higher taxes for tobacco and alcohol, and want to impose a complete ban on advertising of alcohol, but at the same time want to decriminalise possession of class A and class B drugs for personal use, along with decriminalising the trade and cultivation of cannabis completely.

They also want to do away with border controls and promote free movement of people: “We will work to create a world of global inter-responsibility in which the concept of a ‘British national’ is irrelevant and outdated,” they say. But at the same time want an end to free trade agreements and to reintroduce tariffs for trade between Britain and the rest of Europe, tying the import duty levied on a product to the “ecologial impact” of making the goods.