Voting begins in Holborn and St Pancras by-election as 15 candidates seek to succeed Keir Starmer

Polling stations across the north London constituency of Holborn and St Pancras opened their doors on Thursday morning, launching a by-election that will decide who succeeds Sir Keir Starmer as the area's member of Parliament. Around 30 venues, including churches and community centres repurposed for the day, began accepting voters at 07:00 BST. They will remain open until 22:00, at which point the count gets under way and the constituency learns who will represent it in the House of Commons.

The ballot was triggered by the departure of Sir Keir, a former prime minister who announced he was stepping down from his seat in order to concentrate on a role in international affairs. His exit has transformed what was previously a safe political stronghold into a contested open seat, giving voters in the constituency their first opportunity in years to pass judgement at the ballot box on a new representative.

Fifteen candidates have put their names forward to replace him, spanning the political spectrum and reflecting the breadth of opinions held within a diverse inner-London seat. One of the contenders is standing as an independent, a reminder that by-elections often attract a wider field of hopefuls than general elections, with smaller parties and unaffiliated campaigners viewing the contest as a chance to test their message on a receptive, highly engaged electorate.

The relatively crowded field means the ballot paper facing residents will be considerably longer than many are used to. With so many names competing for attention, campaigns will be working hard over the course of the day to ensure their supporters turn out, since turnout rather than raw vote share often decides which candidate prevails in a low-key mid-term contest of this kind.

One practical change that has reshaped recent British elections also applies to this contest: voters are required to present an accepted form of photographic identification before they can be handed a ballot. A driving licence or passport will be accepted, and the requirement places an extra onus on campaigners to make sure supporters not only intend to vote but also carry the correct documentation with them when they arrive at the polling station.

The voter ID rule has proved controversial since its introduction, with critics arguing it risks disenfranchising people who lack official documents, while supporters counter that it safeguards the integrity of the electoral process by preventing personation at the polling booth. Whatever the merits of the debate, the practical effect on a day such as this is straightforward: anyone arriving without acceptable identification will be turned away unless they return with the required paperwork before polls close.

Officials have spent weeks preparing for the vote, training staff, publishing the locations of polling places and reminding residents of the procedures they will encounter inside. The Electoral Commission, the independent body that oversees elections in the United Kingdom, serves as the reference point for guidance on how to vote, what identification is acceptable and where citizens can find details specific to their address.

Because the vacancy arose from a resignation rather than a death or a dissolution of Parliament, the timetable has been set by a formal writ moved in the House of Commons, giving parties a compressed period in which to select candidates, print literature and mobilise their ground operations. Such compressed campaigns tend to reward organisations with established local networks capable of reaching voters quickly.

For the major political parties, the result will be scrutinised well beyond the borders of the constituency. By-elections have historically functioned as a barometer of national mood, offering an early read on public sentiment between general elections. A decisive swing toward or away from the party that previously held the seat would be interpreted as a signal of wider political trends, while a narrow result could be presented by all sides as too close to call.

Attention will also focus on the share of the vote captured by smaller parties and independents, which often use contests of this scale to demonstrate relevance and to pressure the frontrunners into addressing issues they consider neglected. In a seat with a highly educated, metropolitan electorate, debates over the economy, public services, housing and the environment are all likely to have featured heavily on the doorstep in the closing stages of the campaign.

Voters wishing to take part have a narrow window in which to do so. With stations closing at 22:00, the final hours traditionally see a surge of arrivals as people finish work and return home, and party activists stationed outside polling places will make last-minute appeals to undecided residents and to supporters who may otherwise have stayed away.

Once the polls close, ballot boxes will be transported to a central counting venue where officials, supervised by independent agents representing each candidate, will sort and tally the votes. The result is expected to be declared during the night, at which point the successful candidate will be confirmed as the constituency's new MP and will be invited to take their seat in Parliament.

Beyond the immediate outcome, the contest closes one chapter in the political career of Sir Keir, whose decision to leave frontline domestic politics for international work has itself generated considerable discussion about the direction of his ambitions. Whatever the result, the new MP will inherit a constituency with high expectations and a well-informed electorate that will be watching closely from day one.