Gorton & Denton By-Election: Historic Milestones and Key Figures to Monitor
Labour is defending a majority of 13,413 in the Gorton & Denton by-election, a figure that narrowly misses the party's top 50 biggest victories from the 2024 general election. With the vote scheduled for Thursday, history could be made as Labour faces robust challenges from Reform and the Greens. Opinion polls suggest the contest is exceptionally close, with any of the three parties potentially emerging victorious.
Here, we examine the records that might be shattered and the milestones that could be established once all ballots in Gorton & Denton are tallied.
Potential Historic Shifts for Labour
If Labour loses the by-election, it would mark the first time in nearly a century that the Gorton area of Manchester is not represented by an MP from Sir Keir Starmer's party. The Gorton & Denton constituency was newly created at the 2024 general election, replacing much of the former Manchester Gorton seat. Labour held Manchester Gorton continuously from 1935 until its abolition in 2024.
Between 1937 and 1942, the seat was occupied by William Wedgwood Benn, father of former Labour cabinet minister Tony Benn and grandfather of the current Northern Ireland Secretary Hilary Benn. More recently, Manchester Gorton was represented by Sir Gerald Kaufman, who served for 34 years from 1983 until his death in 2017.
Conversely, if Labour secures a win, it will be the first time in nearly two decades that the party has successfully defended a seat at a Westminster parliamentary by-election while also being in government. Labour failed to retain the seat of Runcorn & Helsby in Cheshire in May 2025, losing to Reform by a mere six votes in the first House of Commons by-election of this Parliament. The most recent instance of Labour retaining a seat at a Commons by-election while in government dates back to November 2008 in Glenrothes, Fife.
Vote Share and Majority Analysis
Labour's majority of 13,413 in Gorton & Denton from 2024 is slightly smaller than the 14,696 majority it held at Runcorn & Helsby, which was overturned by Reform in 2025. However, Labour is defending a marginally larger lead in the share of the vote in Gorton & Denton compared to Runcorn & Helsby.
Andrew Gwynne won Gorton & Denton for Labour in 2024 with just over half of the votes cast at 51%, placing him 37 percentage points ahead of Reform, which finished a distant second with 14%. The Greens came third with 13%, the Workers Party of Britain fourth with 10%, and the Conservatives fifth with 8%. In contrast, at Runcorn & Helsby during the 2024 election, Labour led Reform by 35 percentage points, securing 53% of the vote while Reform received 18%.
Reform and Greens: Breaking New Ground
If Reform wins Gorton & Denton, it will have achieved this on a larger swing in the share of the vote—approximately 18.5 percentage points—compared to the 17.5-point swing needed at Runcorn & Helsby. A swing of 18.5 points equates to a net change of 19 in every 100 people who voted Labour in 2024 switching directly to Reform. A victory for Reform would increase its number of MPs in the House of Commons to nine, matching the SNP's total. Additionally, if Reform secures more than 38.7% of the vote, it will set a new record for the party's highest ever vote share at a by-election.
Should the Greens win the seat, it would be the first time in history the party has won a by-election for the House of Commons. It would also mark the Greens' first Commons seat victory in the north of England. Currently, the Greens hold four seats: Brighton Pavilion, which the party has maintained since 2010; and Bristol Central, North Herefordshire, and Waveney Valley—straddling the border of Norfolk and Suffolk—all of which were won for the first time in 2024.
