By BBC News Online's Ed Main

Being mobbed in the streets is not a problem that Darren Johnson has had to contend with in his campaign to become mayor of London.

The Greens were first off the blocks when they elected the former environmental consultant as their candidate in May last year.

But despite the head start Mr Johnson, has struggled to attract a fraction of the publicity accorded to the selection mishaps of rival parties.

When I join the 33-year-old activist on a walking tour of the party's east London heartland of Hackney, he appears relatively unconcerned at not being recognised by any of the voters we meet during the afternoon.

Even in a health food shop the Green-voting owner cannot put a name to the face.

But as we wait outside Finsbury Park station for our escort, Mr Johnson explains that he always knew he would have to play the long game.

And he believes the media are finally starting to take notice.

"I always knew we would have our work cut out to raise our profile, but things are starting to change."

But if Mr Johnson has suffered from a lack of exposure there are other factors which he believes are on his side.

He is certain that Londoners, beset by traffic gridlock, pollution and failing public transport, are increasingly receptive to the Green message.

"Clearly London cannot take this level of cars. Most people recognise this and are ready for radical solutions, more so than they would be in other cities."

What is more, the proportional representation system which will be used in May's poll offers a real prospect of translating that mood into seats in the new Greater London Assembly, he insists.

The Greens estimate that if they repeat the 7.7% share of the vote they won at last year's Euro elections they will land two of the authority's 25 seats.

Mr Johnson is also top of the party's list of candidates. So he would be guaranteed a seat, regardless of the result of the mayor race, and might conceivably hold the balance of power in the assembly.

"There is a real awareness of the electoral opportunities now that we have got through PR," he says.

"I think people who wouldn't have voted for us at a general or local election will vote for us because of the nature of the election."

"I think it will take the Green Party to a new phase.

"We can become as much of a player as any of the European green parties."

Our guide arrives. As befits the only Green councillor in London, Chit Chong, pedals up on a bike on which broken CDs have been recycled as reflectors.

Until last year there was a second Green councillor in the same borough, but he resigned over a child pornography scandal.

Mr Chong, who was elected in 1998, is keen to show how the Greens can put their agenda into practice when given the chance.

But before we head off he points out a rusting bicycle frame which acts as a small-scale example of why London badly needs its new strategic authority.

The abandoned wreck remains manacled to the station cycle rack even though thieves stripped it of anything useful a year ago.

The problem says Mr Chong is that the station forecourt lies at the junction of the areas covered by three boroughs, none of whom will accept responsibility for removing the eyesore.

"This is where the GLA will come into its own and can bang heads together to make things happen," says Mr Johnson.

However, Mr Chong, also an assembly candidate, is not inclined to wait.

He threatens to get some boltcutters and do the job himself if a final appeal for action fails.

Dodging the traffic we cross over Seven Sisters Road out of Haringey Council's jurisdiction and into Mr Chong's territory.

"Welcome to Hackney," the councillor says as we duck into quieter side streets.

The reason for the calm, he explains, is the barriers put up several years ago to stop kerb crawlers straying off the main road into residential areas.

Introduced as an anti-prostitution measure it has also had the side effect of closing rat-runs.

This is the sort of scheme that Mr Johnson would like to see replicated all over London to achieve one of his main aims - a 30% reduction in traffic levels.

He is also keen to deploy congestion charges on motorists and to use them more enthusiastically than the government wants to.

"It is one of the few areas where the GLA can raise revenue," he says.

"But it should not be just about raising revenue it should be tied to reducing traffic. We would look at increasing the charges if traffic reduction targets were not met."

As we walk, he explains why he rejects another Downing Street scheme, the public-private partnership to finance improvements in London Transport.

The Greens favour a bond issue which would bring in private cash, but leave ownership of the network in public hands.

"The experience of rail privatisation has been disastrous. People have no confidence in it," he says.

"There is also a fear that the investment would suit the needs of business but not London."

Passing through some more busy streets we leave the built-up environment behind and arrive at Stoke Newington reservoir.

Swans and geese paddling around against a backdrop of a flotilla of small boats makes for a tranquil scene.

The site manager informs us that this is also home to rare crickets and 1% of all the common toads in Britain.

Mr Chong was an activist in the campiagn, five years ago, that prevented Thames Water concreting over this urban idyll with "eight-storey yuppie hutches."

Although that battle was won, Mr Johnson fears other beauty spots could be at risk unless the assembly adopts a planning startegy that gives greater protection to the natural environment.

"It is vital that we also preserve spaces like this for the community," he says.

He also proposes that the banks of the Thames are protected from unsuitable development in much the same way as green belt land.

Would the Millennium Dome have failed this "blue belt" test?

"On so many grounds: public expense, lack of consultation, poor choice of materials and the fact that it is only a temporary structure," he says.

We hurry on to a photocall with a local newspaper outside a block of flats where Mr Chong has taken up residents' complaints about a mobile phone mast which the council has sited on the roof.

From there we stroll to Stoke Newington Church Street where the councillor is concerned that the high concentration of restaurants is driving out community shops.

However, this does mean we are spoilt for choice when we end the tour with a quick coffee.

Mr Johnson, a veteran of many Green election campiagns, tells me there has been "a sea change" in the way that the media handles his sexuality.

"In the 1994 European elections a local paper did a story about me which was just about how I was gay and just went on about gay issues. Now it is just seen as a biographical detail."

Is he worried that with his rivals all pledging to safeguard the environment and cut pollution there is a danger of the Greens being squeezed out.

"If they all want to fight an election on our agenda. I am happy about it," he says.

"That doesn't neutralise us. It helps us.

"But it is going to be rather difficult for the Tories, particularly as Steve Norris is a former director of the Road Haulage Association."