Sir Keir Starmer may have been named after the founder of the Labour Party, but among his predecessors it is Harold Wilson he admires most. Like Starmer, Wilson was both a pragmatist and a progressive, famously declaring that “he who rejects change is the architect of decay”. It is this shared ethos that explains best why Starmer intends to hand the vote to 16 and 17-year-olds; he is the first prime minister to extend the franchise since Wilson lowered the threshold from 21 to 18 in 1969.

Starmer believes it is essential to restoring the “social contract” with younger generations, whose needs and desires have been ignored by successive governments, and whose faith in democracy is lower than other age groups.

He also sees it, fundamentally, as an issue of fairness. “He’s long believed that if you can serve [in the military], pay tax and reach adulthood in that parliament you should have a say,” a No 10 source said. “Every time the franchise has been widened it has been bitterly opposed. Opponents are on the wrong side of history again this time around.”

Similar arguments shaped the thinking of Wilson’s administration decades ago, as the Swinging Sixties and the Mod subculture personified by rock bands such as the Who gave rise to new ideas about the meaning of adulthood.

Starmer’s opponents see it differently, noting that the trend in recent years has shifted towards raising legal age thresholds, be it getting a tattoo, remaining in full-time education or buying tobacco.

Starmer, following in the footsteps of Rishi Sunak, is pushing through a generational ban on cigarettes for anyone born after 2009. Those nicotine-free teenagers are who he wants to empower at the next election. The UK is to join a handful of countries that have moved to voting at 16 for national elections, including Austria, Argentina and Brazil.

As the veteran Labour commentator John Rentoul recently observed, the challenge for Starmer is “to explain why voting is different from most other things, not why it is the same”.

The fiercest attacks on Starmer come from the right: Nigel Farage has accused Labour of attempting to “rig the system” and secure re-election on the back of a “youthquake”. But to focus on this alone is to ignore a movement that first emerged 40 years ago, and which stretches far beyond the confines of Labour politics.

In 1985, at a time of surging youth unemployment, drug use and crime, a fresh-faced Liberal Democrat MP sought to seize on the growing clamour for change. Aged 30, Jim Wallace, the member for Orkney & Shetland, put forward a youth charter bill to improve educational and work opportunities and to lower the voting age from 18. He argued young people could bring forward “fresh ideas” and had put environmental issues on the agenda “long before they gained political respectability”.

Unlike the environmental movement, his bill failed to catch on.

Wallace, who went on to lead the Scottish Lib Dems and served as both deputy and acting first minister of Scotland, now says “the lot fell on me” because he was the youngest Lib Dem in parliament. Nevertheless, the principle stuck with him and he remains, aged 70, a staunch supporter.

While another three private member’s bills failed in 1991, 1992 and 1999, the cause continued to rise up the political agenda and became a core policy for the Liberal Democrats. It has been in their manifesto since 1992. The SNP followed suit in 1997.

The idea gained popular momentum in the early 2000s, as dozens of youth and democracy organisations formed the Votes at 16 Coalition. It was around this time that a young Angela Rayner, a teenage mother who left school at 16, also began advocating to lower the voting age in her role as a Stockport branch secretary at Unison, the trade union.

While the Electoral Commission advised against the move, by 2007 Gordon Brown was calling for it as prime minister. The Youth Citizenship Commission was established to try to reconnect Britain’s disengaged youth with the political system.

Among the new commissioners was Wes Streeting, who was president of the National Union of Students and is now health secretary. As the 2010 election neared, Labour’s internal National Policy Forum had given its backing, and Streeting, determined the policy should make the manifesto, directly appealed to the man Brown had tasked with writing it.

“The inclusion of votes at 16 in the next manifesto is a litmus test as to how seriously the leadership take the youth movement of the party,” he wrote in a blog post for the LabourList website.

“Ed Miliband: we’re watching you.”

Miliband delivered: Labour’s manifesto promised MPs a free vote on the issue. Brown, however, did not, and the election of David Cameron’s Conservatives doused the hopes of a generation of young activists.

But the election did prove Brown right in at least one respect: fewer than half of the 18 to 24-year-olds registered to vote did so.

In Scotland the genie was already out of the bottle. At the instigation of Alex Salmond, 16-year-olds were allowed to vote on Scottish independence at the 2014 referendum.

More than 100,000 of them voted and at least half chose independence.

Sixteen and 17-year-olds gained the right to vote in Scottish parliamentary and local government elections in 2016, and Wales followed in 2020.

While low turnout among young voters is frequently raised as a reason not to extend the franchise, Wallace believes Scotland has shown the opposite to be true. “The turnout of 16 to 17-year-olds was better than the next tranche of 18 to 24-year-olds in 2014,” he noted.

The habit stuck. In 2023 Edinburgh University found these young Scots had “continued to turn out [at subsequent elections] in higher numbers, even into their twenties, than young people who attained the right to vote later, at age 18”.

Wallace believes this is partly explained by the flurry of educational activity around the Scottish referendum, with “almost every second school holding a hustings”. He added: “It confirms something that I have felt for a long time, which is that the reason why people don’t vote is they don’t know what it’s about.”

Similar trends have been found in Austria, where turnout among 16 and 17-yearolds roughly matches other age groups.

By the time of the Brexit referendum in 2016, the principle of votes at 16 had become widely accepted in Labour. Miliband and later Jeremy Corbyn were committed to it during their leaderships.

After the vote to leave the EU, the argument by Remainers, that 1.5 million ineligible teenagers had been robbed of their future, merely entrenched the belief among senior Europhiles that it was time for change. Many, like Rayner and Streeting, would go on to take seats around Starmer’s cabinet table.

With the policy now set, the question is whether this new cohort of voters will alter the course of the next election.

They number 1.5 million, increasing the size of the franchise by 3 per cent, but large enough to prove decisive in a tight contest. According to an analysis by The Sunday Times, there are 114 constituencies where the size of the incumbent MP’s majority is smaller than the number of 16 and 17-year-olds living there.

Increasingly, age, rather than class or gender, is proving the key social divide in Britain — and it is certainly true that under Corbyn, these younger voters flocked to Labour in 2017.

But those assumptions can no longer be made. Labour’s majority is increasingly under threat from progressive parties such as the Greens, Lib Dems and Corbyn’s new, as yet unnamed alternative.

It is also no longer a given that the youth votes left, if recent European elections are anything to go by. When Germany gave 16-year-olds the vote before last year’s European parliament elections, the populist left and right increased their vote. Sixteen per cent of 16 to 24-year-olds voted for the hard-right AfD.

There was a similar pattern in France, where 31 per cent of 18 to 24-year-olds backed the left-wing France Unbowed at last year’s European election and 26 per cent backed Marine Le Pen’s hard-right National Rally. President Macron’s Renaissance party got 8 per cent.

In Britain, Reform has made a concerted effort to win over millennials and Gen Z. Farage’s presence on TikTok, where these voters increasingly get their news, far surpasses his Labour and Tory rivals. In Warwickshire, where Reform won the largest number of seats in the local elections in May, George Finch, a 19-year-old politics student at Leicester University, is now the leader of the county council.

Reform holds a commanding lead in all-age opinion polls, but surveys by the think tank More in Common consistently show younger voters are still more drawn to Labour and the Greens. This is true even among young men, although they are voting for the populist right in unprecedented numbers. There are also signs that, despite Scotland’s success, apathy among the young remains high. In a recent poll by Merlin Strategy, 49 per cent of 16 and 17-year-olds said they did not want the vote before 18. Only 18 per cent were sure they would vote if there were an election tomorrow.

With so many variables, the change seems likely to have a negligible impact.

According to Wendy Chamberlain, a Liberal Democrat MP who previously co-chaired the Votes at 16 all-party parliamentary group, the only certainty in politics now is “the volatility of the electorate, regardless of their age or other social demographics”.

The bigger problem for Starmer is the perception of other voters. More in Common’s polling found 70 per cent shared Farage’s view that Labour was seeking electoral advantage, and votes at 16 were opposed by 48 per cent to 27 per cent. Luke Tryl, the think tank’s director, says the issue ranks well below the public’s top priorities.

For Wallace, these are challenges not to resile from but to confront head-on.

“It’s a reason to get your argument across to young people, to try and win their vote,” he said. “Whether it’s higher education, better training and apprenticeships, the environment, young people are right to be demanding more.”

Additional reporting by Dominic Hauschild