Sian has lived in London since 1997 and has worked as a medical copywriter, PA, website manager, project manager for a digital start-up, author and transport campaigner before being elected to the London Assembly in 2016.
She has been a local councillor in the Highgate ward of Camden since 2014, was one of the Green Party’s Principal Speakers from 2006 to 2007, and stood as candidate for London Mayor in 2008 and 2016 – she has been selected to stand for Mayor again at the next election.
In 2003 Sian co-founded the Alliance against Urban 4×4s, was a driving force behind the Reheat Britain campaign that secured a boiler scrappage scheme in 2009 and worked for Campaign for Better Transport from 2011 to 2015. She is a member of the Compass Management Committee.
On the Assembly, Sian has chaired the Housing Committee, and been deputy chair of the Police and Crime Committee, and sat on the Oversight and Budget and Performance Committees, scrutinising the work of the Mayor and the overall budget for London.
In the 2021 Assembly year, Sian was chair of the Housing Committee and deputy chair of the Planning and Regeneration Committee.
In the 2022 Assembly year, Sian is Chair of the Transport Committee and continues to sit on the Housing Committee and the Planning and Regeneration Committee.