Resolution criteria

This market will resolve to "Yes" if any sitting Labour Member of Parliament (MP) officially defects to and joins the Green Party of England and Wales before January 1, 2026. The defection must be publicly announced and formally recognized by parliamentary records. This includes joining the Green Party's parliamentary group. Otherwise, the market will resolve to "No".

Official parliamentary records, such as the "State of the parties" section on the UK Parliament website, or definitive announcements from the Labour Party, Green Party, or the MP themselves, reported by reputable national news outlets, will serve as primary resolution sources.

Background

The Labour Party currently holds a majority government in the UK Parliament, with 401 MPs as of the 2024 general election, though this number has seen slight fluctuations since. The Green Party of England and Wales currently has four MPs in the House of Commons. While defections between major parties are not uncommon in UK politics, a direct defection from the Labour Party to the Green Party at the MP level has been less frequent historically compared to defections to other parties like Reform UK.

However, there has been a notable trend of Labour councillors defecting to the Green Party since Keir Starmer became Labour leader, often citing dissatisfaction with the Labour Party's policy direction. The Green Party's new leader, Zack Polanski, elected in September 2025, has publicly stated that he is in discussions with "double figures" of Labour MPs who are considering defecting and would welcome them into the Green Party if they align with its values. Recent polling in October 2025 has also indicated a surge in Green Party support and membership, with some polls showing them neck and neck with Labour.

Considerations

For the purpose of this market, a defection specifically means an MP announcing they are changing their party affiliation to the Green Party. An MP leaving the Labour Party and subsequently joining the Green Party after an intermediate stop would not count.