First Green MP 'a real possibility' says leader

Ms Lucas, an MEP and parliamentary candidate for Brighton Pavilion, said a vote for the Greens should not just be a protest vote.

She pointed to website Vote for Policies, which had seen the Greens "far and away in the lead" with 28 per cent after more than 70,000 people had voted.

The site – http://voteforpolicies.org.uk/ – links users with their preferred political party after they have ticked the sets of policies they agree with.

Ms Lucas told BBC One's Andrew Marr Show: "In terms of people voting for us just as a protest vote, I would contest that a bit – I think that people are increasingly savvy, they know what the Green Party's about.

"People like our policies, what they need to know is that by voting Green, they can get Green politicians elected and at this election, there is that real possibility of getting those first MPs elected."

She said the Greens would not cut public spending straight away but there was a real opportunity for "genuine progressive tax reform" that would seek to make society "more equal".

Money would be saved by cutting Trident, ID cards and road building programmes, she added.