Scottish Conservative wins Aberdeen South in first by-election breakthrough since 2024

Douglas Lumsden won the Aberdeen South seat for the Scottish Conservatives on 18 June 2026. This is the party's first Westminster by-election gain since the 2024 general election — and its first such win at a by-election in Scotland in a considerable time.

The seat became vacant when the previous MP resigned. Lumsden, standing as the Scottish Conservative candidate, defeated Labour, the SNP and other challengers in a constituency that Labour held before the by-election. BBC News confirmed the result, which the UK Parliament's official by-elections register has recorded.

Why this matters

When an MP resigns rather than dies, by-elections tend to carry stronger political meaning. A resignation suggests the outgoing MP chose to leave — which can weaken sympathy for their party and help challengers. In Aberdeen South, the swing was clear: a Scottish Conservative won a Westminster by-election north of the border. The party's Scottish leadership will make much of this result in months ahead.

The result also carries weight because of wider SNP concerns. Stephen Gethins held Arbroath and Broughty Ferry at the 2024 general election with a majority of just 859 votes — barely 1.9% on a 57.9% turnout from an electorate of 76,149, per official election returns. Several SNP-held seats have similarly thin margins. While the SNP already knew this, a Conservative by-election win anywhere in Scotland will heighten anxiety in those vulnerable constituencies.

For the Scottish Conservatives — a party reduced to just one Westminster MP after 2024 — Aberdeen South adds real weight. By-elections draw intense scrutiny and concentrated resources in a single area; winning one signals something different from holding a seat in a general election.

Labour, which emerged as a strong Westminster contender in Scotland after 2024, will need to review this result carefully. A Conservative win in a seat Labour might have expected to compete for is not welcome news.

What comes next

The broader context here is timing. Scottish politics operates across three levels at once — Westminster, Holyrood (the Scottish Parliament), and local councils — which means a single by-election rarely speaks cleanly for the whole picture. Aberdeen South is one constituency.

But whether this swing reflects a lasting shift in Scottish politics, or reflects the temporary dynamics of a mid-term by-election with lower turnout, the next general election will tell more reliably. For a Scottish Conservative party trying to rebuild its Westminster presence, Aberdeen South is the right kind of test case to have passed.