Labour has successfully held the Holborn and St Pancras constituency, a seat previously held by Sir Keir Starmer. Sagal Abdi-Wali secured 45% of the vote, defeating Green Party co-leader Zack Polanski.
The Green Party saw its vote share in the constituency more than triple to 33%, though this was not enough for Mr Polanski to enter parliament. Labour's vote share in the by-election fell by 3.7 points, contrasting with an average 19.3-point fall in four previous by-elections under Andy Burnham's predecessor.
The result follows a period where the Green Party's national polling surge has faded. In March, YouGov placed the party second nationally with 21%, but it is now polling at 10% and in fourth place. Mr Polanski's net favourability rating has also reportedly fallen from -6 to -29 since the beginning of the year.
Jonathan Bartley, former Green Party co-leader, has warned that an influx of new members has changed the party, with some reportedly unaware of its traditions. Rachel Millward, Mr Polanski's deputy, stated that party structures need to become "fully democratic and strategic."