Zack Polanski, the self-confessed eco-populist, won the leadership of the Green Party in a landslide this week. So Westminster Insider Host Sascha O'Sullivan finds out why the Green Party have often struggled to be taken seriously in SW1.

Sascha speaks to the man himself – Polanski – who tells her he is a vegan, who doesn't drive and wants to tell "similar stories as Nigel Farage" but his will be "the truth".

She speaks to Jonathon Porritt, a Green Party veteran and former chair, who says he isn't "completely comfortable with eco-populism".

And Natalie Bennett, Green Party peer and former leader, tells Sascha the party will have to "stir the hornet's nest" to start to get their message across.

Jürgen Klockner, senior policy reporter for POLITICO Europe, based in Berlin, takes Sascha inside the troubles of the Green Party in Germany and issues a warning to their compatriots back in the UK.

"They would promise a Mercedes but turn up with an empty wallet", he says.

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