By-Election Could Signal If Labour On Course For Majority At Next GE

The constituency of Rutherglen and Hamilton West in Scotland holds a by-election for its House of Commons seat today. Usually this would be of little interest to markets. However, winning a significant number of seats currently held by the pro-independence Scottish National Party (SNP) could prove the difference for the main opposition centre-left Labour party between winning an outright majority or falling short and requiring coalition partners in a hung parliament following the next general election.

• Political betting markets give Labour a 91.7% implied probability of winning the seat, which it previously held since its creation in 2005 to 2015, and from 2017 to 2019.
• For Labour to win the requisite 123 additional Commons seats needed for a majority in just England and Wales is very unlikely. During its high-water mark under former PM Tony Blair, Labour held 56 of the then 72 Scottish Commons seats. In 2019 the party won a single seat out of the 59 on offer.
• As such, a strong performance in today's by-election (results expected early on 6 October) is seen as essentially a minimum requirement if Labour is going to translate its sizeable opinion polling lead into an eventual Commons majority.