Image caption Could Natalie Bennett's Greens have an impact on the election result?

The Green Party of England and Wales is ending 2014 on a high nationally, with its opinion poll ratings and membership numbers surging. But the year has also been a challenging one for the party in its stronghold on the south coast of England.

You would be forgiven for thinking you had stepped into the middle of a freight yard.

Piled several storeys high, in the middle of Brighton, are shipping containers that have been converted into houses.

Designed for people who would have otherwise be in hostels or homeless, one of the local residents gives us a guided tour.

"Officially I didn't move in until today," explains Steve, as he proudly shows us his home, courtesy of a scheme run by the UK's first Green council.

It may be modest - a sleeping bag is already rolled out next to the cooker - but for Steve this represents a step closer to getting back on his feet. "It's designed as a stop-gap," he tells us. "I was on the street back in January."

'Chaotic'

The Greens took control of the council in 2011, a year after their first MP was elected, also in Brighton.

The party is running the city without a majority and they have made the task even harder for themselves by deciding not to have a whip - in other words, letting individual councillors decide which way to vote.

"Chaotic" is how Councillor Geoffrey Theobald, who leads the opposition Conservative group, describes the administration.

Image caption Green MP Caroline Lucas supported local workers in their pay fight

"When the so-called leader of the council has to go round individually to each member of the Green group to find out whether they're going to support him or not you can see the situation we're in."

The Greens have certainly upset the electoral arithmetic this year. Nationally, they took 7% of the vote in the European Parliament elections, finishing ahead of the Liberal Democrats.

Now the bigger parties are beginning to realise the Greens could be a factor at the general election too.

"They've started to go from the 2% to 3% they've been for most of the Parliament up to 6%, sometimes 7%," says Peter Kellner, president of the polling company YouGov.

"We're now finding them every so often ahead of the Liberal Democrats."

The decision of broadcasters not to include the Green Party in any leadership debate during the general election rankles because, it suggests, they are still not being taken seriously - but what do people in Brighton Market think?

"They've ruined the town" exclaims one of the stall owners. Another tells us that "everyone moans about the Green Party" before challenging us to find anyone who will confess to voting for them.

Sure enough, the very next person we talk to is a committed Green voter. She says: "I'm very proud to have the first Green MP as my local MP and they're very supportive of the issues I feel very passionate about."

But those who are disappointed with the Greens' record include a sitting councillor and former member of the party, Ben Duncan.

Image copyright PA Image caption Along with the SNP and Plaid Cymru, the Greens could have a major impact on the outcome of the election

"I said a lot of things that upset a few people and the Green Party and I decided to go our separate ways," he says.

He says the Green Party shouldn't simply work within the system but should challenge it, especially over cuts.

"Someone needs to say to the government 'enough is enough; we're not going to do your dirty work for you'," he argues.

"We in local government are going to provide the services that our residents need and I think a lot of people - myself included - would have hoped that the person to take that fight, the first council if you like, would have been the first Green Party council in the country. It hasn't happened."

'Broad church'

We met with the Council leader Jason Kitkat outside Brighton town hall and asked him about divisions within the Green Party:

"It's a broad church and there's a wide variety of views," he concedes. "But we don't split under clear-cut lines. It's not like the old militant days of Labour past. We are united around Green values but we come at it from different perspectives.

"We were elected by the city to do the best we can. But ultimately the people of the city need us to run the city and the budget has been done in a way that, with the changes Thatcher brought in, has to be set."

These internal differences came to a head a year ago, when rubbish piled up on the streets. Refuse collectors and street cleaners went on strike, protesting against the way the Green-run council were implementing equal pay.

And who was standing on the picket line with them but the city's Green MP Caroline Lucas?

Jason Kitkat admits that the former party leader's support for the refuse workers "brought its challenges" but he insists that as council leader he did the right thing:

"Yes, it's been a challenging time for us in local government, as I've said."

Vision vs delivery

Will national political success lead to more such divisions with the Greens?

Party leader Natalie Bennett recently met the SNP's Nicola Sturgeon and Plaid Cymru's Leanne Wood in talks which some observers thought might cover how the parties would use their influence after a general election with a close result next year.

Jason Kitkat expresses what sounds a little like frustration at those in the party, perhaps at a national level, who have the luxury of thinking about the long-term in the abstract whilst he has to get on with the job.

"You have to make decisions today. So that long-term vision is great and is inspiring but we also need to have promises in our local campaigning which can be delivered in the next two, three, four years.

"So that's part of the journey that we've been on that we need to blend the big ambition with the local one."

But what about the future?

"If the Greens are depriving either Labour or the Lib Dems of that left, progressive vote that could help Labour win seats from the Tories or help save Lib Dems MPs from defeat, then the impact of the Greens on the outcome of the election could be very substantial." says Peter Kellner.