Zack Polanski has led the Green Party of England and Wales since September 2025 after winning a landslide leadership contest. Under his tenure the party has tripled membership, secured its first Westminster by-election victory, gained record council seats and mayoral posts, and reached double-digit national polling at times. Recent months have brought scrutiny over an unlawful donation that was returned, questions about his primary residence and council tax payments, and internal party concerns about potential stagnation amid a reported poll slide. On the anniversary of his election, Polanski announced his intention to contest the Holborn and St Pancras by-election triggered by Keir Starmer’s resignation, subject to local member approval. That contest and any associated leadership dynamics within the party represent key near-term factors for assessments of his continued tenure.