The Hamilton by-election in Hamilton, Lanarkshire, Scotland, was held on 2 November 1967. It saw a surprise victory for the Scottish National Party candidate Winnie Ewing. The SNP took 46% of the vote in a constituency which they had not even contested in the 1966 general election, gaining the seat from Labour with a swing of nearly 38%. Ewing did not retain the seat at the following general election, but the SNP have been continuously represented in the House of Commons ever since.
A by-election was called after the former Labour MP, Tom Fraser, resigned in order to take up the position as head of the North of Scotland Hydro-Electric Board. The constituency had been a safe seat for Labour, who had taken over two-thirds of the vote there in every election from 1945 to 1966, when only the Conservatives had stood against them.
In that time, the SNP had been a peripheral movement in Scottish politics. They had taken only 5% of the vote across Scotland in 1966, having stood candidates in 23 out of 71 seats. In the 1950s they had never stood more than 5 candidates or taken more than 1% of the Scottish vote in general elections. However, Hamilton was not the first Westminster seat to be won by the SNP; the party had won a short-lived victory in the 1945 Motherwell by-election. In the years before Ewing's win, there had been other breakthroughs by nationalist parties in Britain - including Gwynfor Evans' similarly groundbreaking victory for Plaid Cymru at the Carmarthen by-election, 1966, a big advance for the SNP at the Pollok by-election, and SNP gains in local elections, including becoming the largest party in local government in Stirling.
The SNP's leadership merely told Ewing to "try to come a good second in order to encourage the members". "As ever," Ewing later wrote, "I overdid it, and as a result my life changed for ever." After her victory was declared, Ewing famously said to the crowd outside "Stop the World, Scotland wants to get on."
Historian Tom Devine describes the Hamilton by-election as "the most sensational by-election result in Scotland since 1945" and Isobel Lindsay called a "watershed" moment in Scottish political history. Gerry Hassan similarly describes it as being a pivotal moment in Scottish politics.