Lynch grew up in Kilmallock, County Limerick, in Ireland before moving to London in 1986. He was the convenor of the London Federation of Green Parties and Co-Convenor of the Green Party Trade Union Group. Lynch owned a shop that was described 'as the most interesting in London' by Time Out Magazine.[3]
Lynch was active in community politics in Finchley. He was also a founder member of The Archer, a community newspaper for the N2 area, and he founded the East Finchley Traders Association. He was on the Administrative Committee of the Finchley Society and spent six years as a voluntary adviser with the East Finchley Advice Centre. Before becoming a member of the London Assembly, he worked for the No-Euro campaign. In addition, he was the founder of an independent newspaper, London Green News.
Within the Green Party, Lynch founded the Green Party Trade Union Group and the London Internationals Group. He chaired the London-Irish Green Group and the London Green Party Animal Rights Group.
As an Assembly Member, Lynch was a member of the London Fire and Emergency Planning Authority (LFEPA), the Metropolitan Police Authority, the Culture, Sport and Tourism Committee, the Planning and Spatial Development Committee, the Health Committee and the Standards Committee (of which he was Chair). He focused on health issues, the homeless, GM crops, fluoride, the aged, disability issues and animal rights. He campaigned successfully to save Cricklewood Homeless Centre and improved the then fledgling Patients Forum of the London Ambulance Service. He organised conferences in City Hall on GM Crops and Non-animal Medical Research. He wrote four papers - Where Have All the Local Shops Gone?, Plastic not Fantastic (against plastic bag waste), Toilets Going to Waste (on the decline in public toilets) and Keep Off the Grass - the Loss of London's Playing Fields. In addition, he asked 157 formal questions to the Mayor on a wide range of issues.