Apart from the fact that most of the Mayor’s initiatives need to be expanded (for example I’d triple the cycling budget), the main policy sticking point between the Greens and Ken Livingstone is that he still wants to build an enormous motorway bridge over the Thames Gateway. This is a policy remaining from his first term in office (before he needed our Green votes in the Assembly to pass his budget) and it would be disastrous for both Londoners and the environment. There will be a huge increase in noise and traffic pollution in east London, and is not the way to solve the transport infrastructure problems facing Londoners.

I’d spend the money on new train and tram services instead and reduce the need for car travel, rather than build more roads, which has never been shown to improve traffic problems.

The woman leader I most admire would be the Green London AM Jenny Jones, who has done wonderful work on the London Assembly for the past  years, implementing many important changes to Mayor Livingstone's budget.

I grew up under Margaret Thatcher, and I believe that with her policies based on the notion that 'there's no such thing as society', she betrayed the British people by destroying social cooperation and community cohesion and introducing an age of naked competitive exchange.

By cutting spending on social welfare, she oversaw a massive redistribution of wealth from bottom to top that took away millions of jobs and led to an increased economically and socially polarised country.

We are still picking up the pieces from the damage she did to Britain's culture, economy, society and reputation. The18 years of Conservative rule, and a further 11 years of conservative rule by the Labour government that followed, have marked a fundamental shift to the right in British politics, which we are barely starting to undo in London.

My plan to close the airport at the end of its lease and replace it with affordable homes and a green industries park would bring much wider benefits to the people of London than more tarmac and low flying aircraft. 

City Airport wants to expand by 50% onto GLA-owned land, and I have pledged not to allow this if I were Mayor.  The increase in pollution, noise and congestion would cause more misery for Londoners in the local area, and the further increase in carbon emissions would spell disaster for the environment.

The majority of City Airport customers are on short-haul flights, which could be replaced by other forms of transport such as trains. The new Eurostar facility from St. Pancras means travelers can be in Paris or Brussels faster than if would if they flew.

People are realising that Green policies are about so much more than the environment. We’re committed to combatting fuel poverty, getting fairer wages, improving human rights and liberties, basic democracy and, of course, challenging climate change.

The Mayoral election is virtually guaranteed to be decided on second round votes (to make sure of this any vote other than for Boris Johnson will help to make sure he doesn’t get 50% to win in round one). In a two-round contest, people are completely free to vote for who they want in the first round, which means if people vote Green first, their second vote will still count as a full vote n the final round.

So, by voting Siân 1, Ken 2, you actually have two full votes counted for the price of one, which I think is a bargain.

It was a very strange ‘debate’ which I don’t think Jeremy Paxman handled very well at all. Beforehand, we saw Tim Yeo (Tory head of the Environmental Audit Committee in Parliament) talking about ‘personal carbon quotas’, which are a Green Party policy we believe are the only way to tackle climate change in a socially just way. But then later, when I mentioned this policy in the debate, Paxman reacted like I’d suggested flying all our carbon emissions to the moon. Very odd, and Ken Clarke and Stephen Hale weren’t much help in keeping the debate to the subject in hand either. I thought I said only coherent and sensible things, but the debate as a whole was a bit of a shambles to be honest.