In the fifth of our series of one to one interviews with London's Mayoral candidates, we met with the Green's Sian Berry to discuss renters unions, air pollution and  being “favourite for third place”.

On housing

Ms Berry, herself a private renter, said her target was to build about 200,000 homes in the capital during the next mayoral term.

She said: “It [solving London’s housing crisis] is just an enormous task that can’t be solved with a single silver bullet.”

She said she would find money for the homes through increasing council tax and continuing the Olympic precept, which is set to expire in 2016 and could be turned into a housing precept, according to the Highgate councillor.

Ms Berry said: “The other parties will try to sign big deals with developers which is the model we have now, which isn’t working.

“We need to break up the land we have into smaller plots.

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“Smaller developers like Pocket homes will take a smaller profit. Their homes are sold at a discount and kept at a discount.”

Ms Berry argued there is plenty of Tfl and public sector land that could be built on, and it was essential to utilise old hospital car parks, disused depots and industrial sites to combat the growing crisis.

She added: “The big developers have got an interest in releasing homes to the market slowly to drive prices up.”

On air pollution

Ms Berry was proud of her party’s policies for combatting air pollution in the capital, which were described as perfect by Clean Air London and said she was disappointed in the other candidates’ pledges.

She said: “It is quite peripheral stuff [from the other candidates].

“Things like electric vehicles are a good thing but we have to talk about reducing traffic and increasing cycling.

“We need to carry on funding cycle super highways and I am the only candidate who is pledging to do that.

“I can afford it because I am putting in a new congestion charge.”

Ms Berry was unable to give specifics about a new congestion charge, but said there was certainly a need for a smarter charge that covered the whole of London in a pragmatic way that took distance, time of day and pollution caused into account.

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On her election chances

Ms Berry, a 100/1 outsider for the City Hall top job, highlighted how she was the favourite for third place behind Labour’s Sadiq Khan and Conservative Zac Goldsmith.

She said: “There is no reason why we shouldn’t have a green mayor for London and in my view we absolutely will one day.

“We have got 16 years of experience within the London Assembly and are making pledges that will last the next 10, 25, 100 years.”

On Transport

Ms Berry plans to create one fare zone for the capital by 2025, which would mean all prices are the same regardless how central journeys are.

She said: “You can change as many times as you like in one journey without paying extra, and the technology already exists to be able to do that.

“You need some incentive to get on public transport as well as a disincentive to use a car.”

Her proudest moments A seasoned campaigner, Ms Berry highlighted the boiler scrappage scheme approved in 2009 as one of her proudest victories.

She said: “We called on the then Labour Government to bring in a boiler scrappage scheme and they did and it paid for itself.

“It kept plumbers going and people were kept in work.

“It was a really, really good scheme and good for the environment.”

On Heathrow

Ms Berry, who is firmly against expansion of any airport, said the fact that the Government had put off the decision until the summer was very worrying.

She said: “The environmental issues cannot be resolved and the noise levels would be literally illegal.

“If it gets granted it still has a huge amount of hurdles to get over.

“As mayor I will be making all the arguments and putting all my lawyers on it.”

Ms Berry added she wanted to propose a frequent flyer levy and said: “Business flights aren’t growing and people taking one holiday a year it isn’t going up.

“What is going up is people with second homes visiting them abroad.

“70 per cent are taken by 15 per cent of people who fly more than three times a year.

“57 per cent don’t fly in any given year.”

Ms Berry described the Heathrow 13, a protest group arrested after blocking the airport’s north runway, as a very brave group.

She said: “The sentences were harsh for something safe, peaceful and non-violent.

“People like that will always be there and will continue fighting.”

On schools

Ms Berry said she would install a deputy mayor for education and give local authorities a greater say in schools planning.

She added: “We need more strategic planning for school places in London. I think the free school plans are failing.”

On Landlords

Ms Berry said as Mayor she would install a renters’ union, which she believed would give private renters a voice and a way of finding out more about their rights.

She added that London should set up a register for its landlords, which would allow renters to compare ratings and avoid dealing with difficult landlords.