Natalie Bennett first joined the Green Party just over a decade ago, in January 2006, and has been its leader since 2012. In the four years of her leadership, Green Party membership has increased from under 14,000 to over 60,000, and has surpassed that of UKIP and the Liberal Democrats. She recently announced that she is stepping down as leader at the end of August, but before that is the EU referendum – she will be up and down the country in the coming weeks campaigning for Britain to remain in the EU.

I met Bennett in the Cambridge Union Society building at an afternoon tea and discussion for supporters, members and the media, where she stresses the importance of engaging everyone to vote in the referendum, particularly the student population. “It would be a real shame, a tragedy,” she says, “if we saw a situation where the over 70s voted us out of the EU, a decision that’s going to have a massive long term impact on the lives of the under 30s.

“Unlike in the general elections, the council elections, or Westminster, where lots of people live in safe seats, and people feel like their vote doesn’t count, the reality of this vote is that everyone’s vote counts exactly the same.”

Bennett warns against complacency when it comes to the referendum: “I think the temptation in somewhere like Cambridge is to think ‘oh, we know Cambridge is going to vote to remain in the EU’ – but that doesn’t matter at all. The only thing that matters is the national tally, so it’s really important to stress that everyone’s vote matters in this. We really need everyone who wants to stay in the EU to go and vote to stay.”

When I ask her opinion on ‘Lexit’, the left-wing Brexit campaign, Bennett “understand[s] people being critical of the European Union. We are critical of the European Union, that’s why we’re called ‘Greens for a better Europe’ as a campaign.” Bennett insists, however, that leaving the EU is not the solution, listing her criticisms of Westminster – “our first-past-the-post electoral system, the unelected House of Lords, the influences of big multinational companies over the government. 

“All of those things are problems with Westminster, but the answer is not to give up on democracy – the answer is to stay in and reform it.”

Bennett warns about the consequences of a Brexit vote, joking “I’m presenting a nightmare here, but it could come true! Britain has voted for Brexit, and we have Prime Minister Boris Johnson, going on bended knee to Washington, possibly to President Trump, and saying ‘We want a US-UK free trade deal, and we will sign anything you want us to.’” That, she implies, could be the result of voting to leave.

The solution to stopping such a trade deal, and the EU-US trade deal 'TTIP', will come from within the EU, she suggests. Bennett mentions “the civil society campaign across the EU, which saw 3.5 million people sign the petition, that saw 250,000 marching on the streets of Berlin against TTIP”, and argues that “being together, with that civil society, with that campaign… is the way to stop TTIP.”

I question Bennett on what the Green Party offers students that Labour does not, since the Greens share many stances, including opposition to Trident nuclear weapons and to austerity, with Labour leader Jeremy Corbyn. What differentiates the Greens for Bennett is their “complete philosophy that incorporates the environmental, the social, and the economic together.

“In the terms of our philosophical basis, economic and environmental justice are indivisible… we have to live within the environmental limits of our one, fragile planet… that has to be the foundation of everything.”

Bennett is encouraging of student engagement in politics, reinstating her belief that “politics should be something you do, not have done to you”. She urges wannabe activists to “build up your ability to do politics by starting with the local, small scale: something in your college that you want to change and you think other people want to change too, something here in Cambridge, the street you live on. 

“It’s from those small foundations and all of those groups thinking together that you can then build something big,” she says with a smile. She gives the example of 17 year-old member of the Youth Parliament, Owen Winter, and how his petition demanding proportional representation quickly amassed 230,000 signatures.

“Saying ‘I want to stop climate change all on my own' is a big ask, but if you see something and think 'We need to do something about it', give it a go, and one individual [...] can make a big difference.”

I ask Bennett how the Greens will be making their voices heard in Cambridge without the Market ward seat on the City Council, which they lost to the Liberal Democrats in the local elections in May. “What we’ll be doing will be campaigning – we’ve got a message that’s a unique message here in Cambridge, around Britain and indeed globally”, she responds, and she points to issues like air pollution which, focused on by the party years ago, have now come into the forefront of political debate. 

“Many of the things the Green Party has been campaigning for, things like 20 mph speed limits where people live, work, and shop, like the living wage, we might not have achieved all of them, but they have moved from being seen as a fringe issue very much into the mainstream.”

Later that day Bennett speaks at an evening talk and Q&A session at Newnham College, where she cements her case for campaigning to stay in the EU, but also her frustration at how much of the referendum has been conducted.

“In terms of the EU referendum, it’s an absolute disgrace that 16 to 17 years-olds haven’t got the vote”, she argues, as “this is a decision which is going to have an impact for decades”. 

“This would have been the logical place to change to give them the vote in all elections”, Bennett suggests, and she tells the crowd that in her experience, the age-group is “at least as well informed about politics as every other age group. Certainly they could be more informed, but so could 70 year-olds.”

Sixteen to 17 year-olds are not the only ones missing out, implies Bennett. “EU citizens should have the vote, Britons who have been away from the UK for more the 15 years, certainly those in continental Europe, should have the vote, because it’s of huge interest to them. The narrowing of the electorate is a democratic disgrace… people affected by the decision should have a say.

“David Cameron really hasn’t helped us with this, with the timing – exams, holidays, Glastonbury” Bennett quips, and reminds voters about postal votes, proxy voting, and being registered at the right address.

Overall, Bennett’s case for staying in the EU seems impassioned and heartfelt. “Let’s acknowledge that people in the rest of Europe want us to stay as part of Europe too. We’re family, we’re neighbours, we’re part of one European community. Let’s stay part of that community, and work together to build something better.”

The EU referendum takes place on the 23rd June. The deadline for registering to vote is June 7th.