Co-Leaders: Jonathan Bartley & Siân Berry AM

Jonathan and Siân were elected co-leaders on a joint ticket in 2018. This is Jonathan’s second term, as he had served as Green Party co-leader for two years previously with Caroline Lucas.

Jonathan and SianSiân and Jonathan stood on a joint platform to become England and Wales’s third party, to redirect economic policy away from an obsession with growth and towards well-being, and to work tirelessly to get climate change to the top of the political agenda.

Jonathan joined the Green Party in 2010, shortly after encountering then Conservative Party leader David Cameron. He was waiting to attend a hospital appointment at the Evelina Children's Hospital with his son Samuel and challenged the future Prime Minister about the Conservative Party’s manifesto pledges, arguing they’d increase the segregation of disabled children. David Cameron’s denial was later shown to be wrong by Channel 4 FactCheck.

A descendant of Irish farmers on one side and Quaker prison reformer Elizabeth Fry on the other, Jonathan has a passion for social justice and studied Social Policy at London School of Economics. He worked in Parliament on a cross-party basis from 1994-1998 and used that experience in his roles as vice chair of the Electoral Reform Society and vice chair of Yes to Fairer Votes campaign during the 2011 referendum.

He has also served as chair of Centre for Studies on Inclusive Education and helped establish the Accord Coalition with British Humanist Association and teaching unions to reform faith schools. In 2000 Jonathan set up an internet venture that has since raised over £1 million for work in the global South.

In 2015 Jonathan was the General Election candidate for Streatham, increasing the Green vote locally fivefold. A dedicated local activist, he also played a pivotal role in getting the first green councillor elected in Streatham from a starting point of 4th place. In the breakthrough local elections of May 2018 Jonathan was elected as councillor for St Leonard’s ward in Lambeth. With five councillors, the Greens are the official opposition on Lambeth council, for which Jonathan is the Leader.

A proud Dad of three children, Jonathan spends his free time jamming with his blues band, the Mustangs, and was nominated for Blues Drummer of the Year Award in 2010.

Siân has lived in London for 20 years, and grew up in Gloucestershire before studying materials science at university. She joined the Green Party in 2001, politically energised by the twin threats of globalised capitalism and climate breakdown. This prompted a career change from working in pharmaceutical marketing as a copywriter to join the charity and public sector in range of tech and campaigning roles.

From 2011 Siân worked for four years as a campaigner at the charity Campaign for Better Transport, where she supported local communities and campaigns trying to stop new roads from destroying the countryside, and helped to win new funding for walking and cycling from the Government.

Siân has stood for the Greens in council elections in her home borough of Camden since 2002. She retained her deposit in Hampstead and Highgate constituency in 2005 and was elected to Camden Council in 2014.

Siân has been the Green candidate for Mayor of London twice, in 2008 and 2016. She won third third place for the second time for the Greens in 2016 (after Jenny Jones came third in 2012) and has continued to hold Mayor Sadiq Khan’s feet to the fire since being elected as a member of the London Assembly, alongside Caroline Russell, in the same year.

On the London Assembly, Siân has served as deputy chair of the Police and Crime Committee and is chair of the Housing Committee. She works on a wide range of issues, and her advocacy on behalf of Londoners has helped highlight hidden homelessness, win new funding for youth services and improved renting rights, while standing up for for civil liberties and against the loss of council housing. In 2018 the Mayor dramatically changed his policy and created a new right for residents on estates to have a ballot over demolition plans, after a long and successful campaign by Siân and resident groups across London.