Caroline Lucas stands outside parliament addressing a crowd of anti-fracking campaigners. She is in her element. This time, there will be no sit-in, no arrest, no charge for disturbing the peace. The smart, personable Green MP simply says her bit, announces there are now 361,736 signatories calling on MPs to reject fracking under homes, then takes the petition into the Commons.

It’s not a huge gathering, but big enough. And it’s quickly apparent that the people here don’t regard the Greens as simply a protest party; they see them as real players in a rapidly evolving political landscape. These are activists who have fallen out of love with the Lib-Dems and Labour, who despair of British politics’ traditional three-party structure – and yet they all seem surprisingly optimistic. They talk about the mismanaged planet, how the mainstream parties are in the hands of the corporates, the Green surge. But Lucas knows about false dawns, and is not getting carried away. For all the talk of the Greens being on the cusp of something big, the party still has only one MP, Lucas, the member for Brighton Pavilion. What’s more, it runs only one council, Brighton & Hove – and even that is minority controlled. Lucas is well aware that this does not a revolution make.

Their leader takes a giant tumble, but the Greens keep marching on Read more

A few days after the anti-fracking gathering, we meet inside parliament. Lucas’s office is impressive: a staff of four women, decent space, a lively atmosphere. Then you remember this is the only office the Greens have in the Commons, and things begin to look different. Her own room, at the back of the office, is so tiny that most of her awards are deposited in the fireplace, though that might be a question of style as much as space. There’s Environmental Parliamentarian of the Year, won in 2010 (“It did mean a lot, but it would have been just awful not to have won it the first time the Green party’s in parliament”), Red magazine’s green personality of the year, and last year’s Patchwork Foundation MP of the Year, awarded to the MP who has done most to work with deprived minority communities in their area. “That meant a huge amount, because it’s nominated by people in your constituency. It shows that even as a single MP from a small party, you can get things done.” A red banner is draped around the fireplace – it reads, “Well behaved women rarely make history.”

Facebook Twitter Pinterest Lucas being arrested at a 2013 anti-fracking demo. Photograph: Dave Evans/Demotix/Corbis

The funny thing is, if you did a poll about the best-behaved parliamentarians, Lucas might well be up there. She is polite, softly spoken, smiley, elegant, proper – the perfect counter to the crusty green stereotype. In her five years in parliament, she has shown a desire and ability to work with MPs from other parties – crucial when you’re a singleton. Yet this is the same woman who has a conviction for breach of the peace, dating back to a 2001 CND sit-in outside the Faslane Trident nuclear submarine base. In 2013, she was charged with (and subsequently cleared of) obstructing the highway and failing to comply with a police request to move when protesting against Cuadrilla’s exploratory drilling for shale gas in Balcombe. In the same year, during a Commons debate, she was ordered to cover a T-shirt displaying the slogan ‘“No More Page Three”, to comply with Westminster’s dress code.

I have never met a more goody-goody troublemaker, I say.

She grins. “Well, that can be quite a good thing, can’t it? You can be a Trojan horse.”

I have seen whips pushing people through the aye and no lobbies. They don’t know what they’re voting on

In May, she might well make trouble for the mainstream political parties. Lucas knows that if the Greens have a good election, it could be bad news for Labour and result in a Conservative victory. She says that a second Tory term is the last thing she wants, but, in the long term, it could be the best thing possible for the Greens if Labour lost. “That wouldn’t be the outcome I wished for. But I would think, ‘Now, for heaven’s sake, Labour, you have to embrace electoral reform’ because we are operating under a voting system that is creaking at the seams, that is not fit for purpose.” This would probably come in some form of proportional representation, which could only empower the Greens.

In the meantime, she is focusing on the most immediate goal – to retain her own seat, and help win Bristol West and Norwich South. If this comes to pass, she hopes the Greens might prop up a minority Labour government. “I think a progressive alliance of Greens, SNP and Plaid Cymru, alongside a minority Labour government, would better reflect what most people want in this country, rather than a majority Labour government.”

But Lucas isn’t counting her chickens. She has been here before, and that ended in disaster. In the late 1980s, she was press officer for the Green party. It was a terrible time for the planet and, briefly, a great time for the party. For the first time, people were talking about global warming, holes in the ozone and environmental apocalypse. Twenty thousand people joined the Greens, the party was invited on to Question Time and, astonishingly, won 15% of the vote in the 1989 European elections. And then they blew it. The party had no infrastructure, didn’t know how to hold on to new members, and became a laughing stock when they said they didn’t believe in leadership. “It was extremely frustrating,” Lucas says today. “It was an incredibly difficult time.” In the early 90s, the Greens were further tainted by association when former chairman David Icke announced that he was the Messiah. Even today, Lucas argues that, between 1988 and 1991, Icke was a good chairman, increasing the party’s profile. “It was when he went on to think he was the son of God that things got a little bit more complicated.” The Greens became known as the potty party, and that was pretty much it for a decade.

‘We need to put a greater support team around our party leader,’ says Lucas of the Green leader Natalie Bennett after two car-crash interviews. Photograph: BBC

Lucas spent 10 years working for Oxfam as a press officer, policy adviser and team leader for trade and investment, remaining a Green party activist throughout. In 1999, she left Oxfam and was elected as a member of the European parliament for the south-east England region, which she held in 2004 and 2009. In 2008, she was elected the party’s first leader, gaining 92% of the vote, and finally, in 2010, she became Britain’s first Green member of parliament. Often, it has appeared to the public as if Lucas is the Green party, but in 2012, she announced she was standing down as leader, “in order to broaden opportunities for the range of talent in the party and to raise the profiles of others aspiring to election”. The former Guardian journalist Natalie Bennett won the subsequent election, starting another chapter in Green history.

Now Lucas has written a book about her time in the Commons, called Honourable Friends? Parliament And The Fight For Change. Her conclusion is that many MPs are neither honourable nor friends. There are exceptions – she has worked constructively with the Conservative MP Sarah Wollaston on parliamentary reform – but on the whole her experience of parliament has been dispiriting. She had no idea how archaic the Commons was until she got there. She talks about how voting is a much simpler process in the European parliament, because it’s done electronically; here, it is often impossible to work out what an amendment means because of labyrinthine cross-referencing. She suggested that a 50-word summary of each amendment be introduced, but this met with huge resistance, she says, because it takes away the power of the whips. “I have seen whips literally pushing people through the aye lobby and the no lobby, even if they are remonstrating and saying, ‘I don’t want to vote this way.’ They are pushed over, and once you go over the entrance way, you can’t come out again. You just have to hide in the toilets. People don’t know what they’re voting on, and I think that’s shocking.”

Shocking is a word she returns to time and again when talking about parliament, most often in the context of the power of the whips. Often, she says, whips will deliberately assign MPs to work on committees where they have no expertise, so they pose no threat. “There is a lot of bullying,” she says. Does she have contempt for the parliamentary system? “Yes, I think I do. That’s not a word I would use lightly. We pride ourselves on our democracy, but when you see the way it actually works, I think it is worthy of contempt. MPs should be doing a hell of a lot more to reduce the power of the whips and to increase the power of the backbench MPs; to actually have people here to make a difference, rather than simply toe the party line.”

Does she feel more of an insider these days? “No. That’s why I have my red banner. When I was first understanding how this place works, Margaret Beckett said, ‘You’ll get used to it’, and I turned on her. If people have got used to this place, that is not the way it should be. You should never get used to it.”

She does not have much time for the party leaders, either. She despises Cameron’s policies: “The Conservatives have overseen some of the most brutal cuts, to the most vulnerable people, meted out in modern history.” Is she surprised that Cameron has championed the Greens’ right to take part in the proposed leadership debates? “Yes, especially seeing as he’s refused every request for a one-to-one meeting. It’s a little bit transparent what he’s doing. But certainly it’s helped us out in terms of being part of the debates.”

As for Nick Clegg, she says his reversal on tuition fees is responsible for much of the cynicism about British politics today. “What I can’t forgive is that it was always difficult as an MP to say, ‘Trust me’, but you can’t say it at all now.”

While Ed Miliband is a more natural bedfellow, she believes he is weak. “The lack of a convincing opposition is what’s helping the Green party. Even if people don’t agree with us, I think they respect the fact that we take a position. The way that Labour trooped through the lobby just a few weeks ago, following the Conservatives to vote for George Osborne’s charter of budget responsibility, was a case in point. They signed up to yet more austerity, because they were afraid of being [seen to be] ‘profligate’ with the nation’s finances.” She finds it astonishing that Labour doesn’t do more to defend its economic record. “It was not Gordon Brown and previous Labour administrations overspending – it was caused by an international financial crisis. It drives me mad that, on Question Time, I’m the one defending Labour’s legacy. It’s like, ‘Hang on a minute, can you please do your own work?’ It makes it harder every step of the way to challenge the government’s austerity when you haven’t got the official opposition calling them out on it.”

Facebook Twitter Pinterest Lucas with Ed Miliband in 2011: ‘It’s clear that Labour are worried about the Green vote. But the more Labour diss the Greens, the more support we get.’ Photograph: Anna Gordon/The Guardian

In some ways, Lucas is an unlikely radical. She was raised in Malvern, Worcestershire, by parents who were conservative with a small and big C. Her father ran a small heating company, and sold solar panelling, even buying some for the family home. It wasn’t a political issue for him, it was simply business. Did the panels increase her environmental awareness? “No, I think it probably set it back. In those days, the motor for them was so loud that I’d be woken up at 5am in the summer when the sun starts coming up. I absolutely hated those bloody panels.” She laughs.

I ask how her parents felt when she was convicted of breaching the peace. “My dad found out about it at the Rotary Club. He rang and said, ‘I hear you’ve been arrested – are you all right?’” Was he embarrassed? “Yes, he may well have been a bit. My parents are not people who would want to rock the boat. They wouldn’t break the law.”

The young Lucas went to a private school for girls, where she befriended a girl whose mother was leftwing and literary. Suddenly the world looked so much bigger. “Their house was full of books, her mum read the Guardian, they had Body Shop stuff in the bathroom, and it was like a whole new way of thinking and being. It was extraordinary.” As she talks about it now, almost 40 years on, you can still hear the wonder in her voice. “We went to Paris together. Her mother was fluent in French and we were doing French A-level, reading Le Grand Meaulnes. The author, Alain-Fournier, met this woman on a bridge in real life, and her mother was the kind of person who knew which bridge it was and we would stand there. It was just... the blinkers fell off your eyes.”

She began to look at the world anew. She did an English degree at the University of Exeter, spent a year studying Buddhist philosophy and history of art in America, and then began a PhD. “My interest was in renaissance literature, looking at how men were writing for women in the 1590s, a time when many women were being taught to read but not to write.” This meant women could absorb information from men but were unable to inscribe their own reality. “There were wonderful romances with very strong female characters, who without exception were killed off on the last page. So you will see, dear reader, having a wonderful time and following your own heart doesn’t pay and you must therefore be very obedient to the men in your household.”

At a Commons debate on media sexism

Halfway through, she realised she was more interested in feminist and environmental politics than academia. She turned the PhD into a book, which got taught on university courses, and became involved in the incipient Green movement. Lucas says Jonathon Porritt’s book Seeing Green enabled her to make sense of the world. “It brought together all the things I was concerned with – feminism, CND, the environment – into a single package. It started to talk about some of the causes of the problems, rather than just the symptoms.” Politically, she had felt pulled in different directions, but Porritt’s book presented a coherent philosophy that addressed her concerns. “He showed that the values that lead people to exploiting the planet are the same set of values that may well lead you to thinking nuclear weapons are the answer to security, which may well lead you to having a more patriarchal position in the role of women, and these things are not all entirely separate.”

Lucas, now 54, says the Greens’ most popular policy today is to bring the railways back into public ownership when the franchises expire. She can’t understand why Labour has failed to back such a populist policy. “I don’t think Ed Miliband has the courage of his convictions. He’s scared he’ll be painted by the rightwing press as a throwback to the time of the ‘big state’.” Does she think Labour fears the Greens? “Well, I would imagine that’s why Sadiq Khan was made head of the anti-Green unit. It’s clear that Labour are worried about the Green vote, but the more that Labour sets out to diss the Greens, the more support we tend to get, because it’s so transparent.”

It’s also true that the more support the Greens garner, the more closely their policies are scrutinised. When we meet, party leader Natalie Bennett has just given an interview to Andrew Neil that could be described as car-crash television. Neil exposed the fact that the party’s much-touted citizen’s income had not been accurately costed and was unaffordable. More controversially, he pointed out that party policy said it supported the right of people to belong to any party of their choice: did that mean it was OK to be a member of Al-Qaeda or IS? “Exactly,” Bennett replied. “What we want to do is make sure we are not punishing people for what they think or what they believe.”

Lucas says that Neil quoted policy out of context. Even so, it was embarrassing, wasn’t it? “Yes, it was. It was not helpful.” So how do the Greens ensure they are not caught short like that again? Lucas answers slowly and carefully: “I think there needs to be a much clearer briefing process for all our spokespeople, so we’re able to handle interviewers like Andrew Neil. Like any party that is suddenly under the spotlight, we are doing a bit of catchup in terms of being able to cope with a new degree of scrutiny. It’s a fantastic opportunity for us, but there will be mistakes made along the way.”

If she had been in that position, what would she have said? “I would have said very clearly that the party has a proud record of non-violence, and the suggestion that we would ever be supporting Al-Qaeda or IS or any terrorist group is ludicrous. I would have tried to explain there’s a distinction between a policy handbook, which is the overall thinking of the party over 30 years, and what will be in our election manifesto.”

Earlier this week, Bennett gave another disastrous interview, to LBC Radio, in which she appeared confused by her own housing policy. “We’re all human,” says Lucas. “We all have the odd off day, and she openly acknowledged hers. She wasn’t well, and she had a bad interview.” Does Lucas wish she was still leader? “No. When I see the incredible workload Natalie gets through, I think she’s doing an amazing job. We need to put a much greater support team round our party leader and our deputies. We need to think about what other parties would have, in terms of the machinery to make sure people are properly briefed. We are working her to the bone.”

Part of the reason Lucas stood down, she says, is because she did not think leadership was compatible with being an effective MP. “I wanted to spend more time in Brighton. If you’re not a good constituency MP, then you’re nothing.” But why would it be tougher for Lucas to lead and be an MP than it is for Cameron or Miliband? “Well, my majority’s a lot smaller,” she says (it’s 1,252). “And as the first Green MP, you’ve got more to prove. People have taken a punt. They’ve acted on faith. Therefore I felt more pressure to make sure their first experience of a Green MP was a positive one. If you get a dud Tory or dud Labour member, it doesn’t make you feel the whole party is incapable of producing a decent MP.”

She is acutely aware of how desperate Labour is to skewer her. “Labour really want it back. I’m number 19 on their hit list.”

Lucas with her husband Richard. Photograph: Courtesy of Caroline Lucas

It’s mid-February, and Lucas is canvassing in Brighton. She has lived here for the past six years with her family; she and her husband Richard (a teacher and former Warwickshire cricketer, whose claim to fame is bowling out Viv Richards) have two sons, aged 21 and 18, both of whom vote Green.

If you want a symbol of all that the Greens have achieved in the past five years, look no further than Brighton. If you want a symbol of all they’ve messed up, ditto. All day long, I do not meet a local who doesn’t like Lucas, but I also don’t meet anybody who isn’t scathing about the council. Its failings are the stuff of farce. This is the Green council that cannot recycle its own rubbish. Doesn’t it have the worst recycling record in the country, I ask Lucas. “Not actually the worst,” she says. “I think we’re about 15th off the worst.” It’s a painful admission.

The public does not give her an easy ride over it. John Pope, a retired businessman carrying the Telegraph under his arm, wants a word. “My point is refuse,” he says. It’s everybody’s point. From the quietly disappointed to the loudly enraged, Lucas’s renowned tact is tested to the full. Yes, she says, it is shaming, but the reasons are complex, and to do with equal pay. She looks exhausted by the end, and I feel sorry for her. She would probably hold on to her seat with ease if she didn’t have to counter the council’s rubbish legacy.

Sally Cranfield, who is helping to canvass this morning, argues that the complaints are a measure of the party’s success. “First Green council, first Green MP, and it’s had enormous challenges. The Green council has been fantastic in the face of huge government cuts, and being a minority administration, but they have faced an awful lot of flak.”

Does she miss Lucas as the party leader? “I have to be absolutely honest, yes, I do miss her. There have been some hard questions asked recently, and I just think, ‘Oh, Caroline would have answered that perfectly, or so much better.’”

We’ve been out in the freezing cold for a couple of hours. Lucas’s nose is red, and she’s hugging herself tight in her winter coat. As we retire to a cafe, she defends Bennett again, pointing out that the Green surge has taken place under Bennett’s leadership, not her own.

We sit down with our coffees, and I tell her I have some simple green questions for her. Great, she says.

Have you got a compost heap? “Yes. Have you?”

Do you shop at a supermarket? “Sometimes I do, yes.”

Which one? “This is really unfair. A combination of Waitrose and Hisbe – which stands for How It Should Be, and is an amazing ethical and organic supermarket.”

Are you a vegetarian? “Yes. No, I’m not, I eat fish. I stopped eating meat because it felt like something one could do practically that would make a small difference.”

She says she thinks I’m trying to trap her. “I can’t relax with you any more. Hahahaha!” She laughs, but the smile has gone.

Does Lucas wish she was still leader? ‘No. As the first Green MP, I’ve got more to prove. People have acted on faith'

What is your most un-green guilty pleasure? “My son’s studying in the States and I don’t feel great about getting on the plane to visit him, but I’m still going to do it....” She stops. “You know, the reason I don’t like these questions is that it makes it sound as if you have to be particularly self-sacrificing in order to be a Green, and what we should do is make it cheaper so everybody could, say, go to Europe by train.” She hates the subtext. “I’m not liking the signal that it gives out. It could be written up to say all Greens have to be vegetarians, not fly, and have a compost heap, and that is not the case.”

It’s good to see the tough, prickly side of Lucas. Now I can see how combative she can be when necessary. Would she like to be prime minister one day? She bursts out laughing before giving a straight answer. “I really would like to have access to some power, yes. I’m not in politics because I’m playing about. I’m wary of your headline – ‘Caroline Lucas wants to be prime minister’ – but most MPs are there because they want to have access to power. So yeah.” Another pause. “I don’t think I’m going to be prime minister just yet!”

First, she has to hold on to her seat. In terms of legacy, Brighton is everything for the Greens. And Lucas’s record and reputation might well determine whether more Greens are elected to the next parliament. It’s such a massive moment for you, I say: if you win three seats, you may well end up part of a progressive alliance; if you lose your seat, you would be back to square one. I can virtually see her stomach churn as I say it. “I know,” she says. “I don’t want to think about it. It’s too awful to contemplate.” She says she’s been having dreams about this May’s election night count. “It’s a really scary time. The prize is so huge - and the sense of loss would be even huger.”

• Honourable Friends? Parliament And The Fight For Change, by Caroline Lucas, is published next week by Portobello Books at £14.99. To order a copy for £11.99, go to bookshop.theguardian.com or call 0330 333 6846.