By Gillian Hargreaves
Political correspondent, BBC News
It might seem easy to dismiss the Green Party as a credible political force.
Caroline Lucas criticised Labour's record in power
Some of the names on the security passes at their annual conference last week were handwritten, the venue a cosy Hove Town Hall.
But do not write them off - they have big ambition, and a new sense of confidence was evident at the annual gathering for party members in England and Wales.
They may have been unable to increase their number of MEPs at at the European elections in June, but they polled a record 1.3 million votes, enough to establish them as a real threat to the mainstream parties.
Now they are turning their attention to Westminster and the next general election.
Party leader Caroline Lucas, one of their two MEPs, was in upbeat mood when she made her speech to conference on Friday.
At the general election, which must happen within the next nine months, Ms Lucas is focusing her personal ambition and the party's campaigning efforts on the Brighton Pavilion seat held by Labour's David Lepper.
Her speech sounded in part like an election bid.
"A transition to a post-carbon world doesn't have to be about sacrifice," she told delegates.
"It's about jobs, it's about a more equal society and it's about a way of life with the potential to be far more fulfilling than the turbo-charged consumerism which is peddled by politicians today.
"And that's why we say that our government's inaction is nothing less than a political crime.
"In eight months time, we'll be fighting the most critical general election for a generation.
"It's not only critical for us as a party, but for the direction this country takes as a whole, over the coming decade and beyond.
"Are we to continue down the road of growing inequality and cynicism as we drift towards an environmental catastrophe?"
On the surface Ms Lucas's ambitions look promising.
The Greens have a strong presence in Brighton, with 13 local councillors. Ms Lucas began her speech by telling delegates the party had come first in Brighton at the European elections, with 6,000 more votes than the Conservatives and "more than double the number of votes for Labour".
But success in European and local elections does not necessarily an MP make.
The BBC's polling expert David Cowling points out that the Greens received over a million votes in the 2004 European election but when it came to a general election 10 months later only quarter of a million people voted for the party.
He says history shows they do well in elections that the voting public perceive as not important but when it comes to national issues people shy away from going Green.
There are new challenges for the Greens too.
Labour, the Conservatives and the Liberal Democrats are increasingly trying to out-green the Greens.
When David Cameron cycles to work or talks about global warming he gets acres of news coverage and Labour has been able to make CO2 emission targets legally binding - precisely because it is in government.
The Greens' unique selling point is disappearing fast - which is why this year the party leader heavily criticised Labour's record in office.
"After more than a decade of Labour government - a Labour government - inequality is higher than before they came to power.
"And one in five children in Britain is living in poverty.
"And yet this government's response to the current economic crisis is creating more inequality, not reducing it."
Caroline Lucas showed in her speech that she is keen to talk about issues other than the environment: health, education, trust in the political system and the economic downturn."
"For years, Greens have been warning against the lethal cocktail of liberalisation and deregulation which have fuelled this recession," she told delegates.
The Greens had "sounded the alarm" about the housing market, hedge funds and currency speculation and was the only party willing to defend the public services against "swingeing cuts".
But their core appeal remains to the environmentally-aware voter.
And in these straightened economic times even the greenest among us might question the cost of buying organic food, or installing a new environmentally friendly boiler, when they are facing the threat of redundancy or repossession.
The Greens counter this by pointing out that their 1.3 million mandate in the European elections shows they are recession-proof.
We will have to wait and see if this support can be converted into success at the next general election - and whether voters allow them to take their long-coveted place at Westminster.