 Berry was elected as the Green Party's female Principal Speaker unopposed in autumn 2006, succeeding Caroline Lucas MEP and, working alongside male Principal Speaker Derek Wall, served until Autumn 2007 when Lucas resumed the post following an election.She wrote a regular blog for the "New Statesman" magazine from November 2006 – July 2008.On 12 March 2007, the Green Party announced that Berry would be the party's candidate in the 2008 London mayoral election, after she received 45% of the votes in the London Green Party's internal election.