The Electoral Reform Society welcomed the move, saying it would “strengthen democracy” and get young people into the habit of voting. But Sir Simon Clarke, Director of think Tank Onward, called the Labour announcement “a cynical attempt to rig the system in their favour.”

Sir Simon, a former Communities Secretary, said it made no sense to allow people to vote when they could not buy a pint, rent a flat or even leave education entirely. He said: “Let’s call it what it is: gerrymandering in a school uniform.”

Younger people have traditionally been more inclined to vote Labour than the elderly, and polling company YouGov estimated that 41% of voters aged 18 to 24 backed Labour in the 2024 general election, compared to 28% of those aged 60 to 69.

But the current Labour government may not be popular with younger voters, said polling expert Professor Sir John Curtice. He said: “Labour lost a lot of ground among the youngest age group at the last election.

“This may be a change that has come too late for Labour. The party that now seems to have the most vested interest in the change is actually the Greens.”

He also pointed out that under-18s would make up a small minority of voters, with population data showing there are 1.4m people aged 16 and 17 in England and Wales, while 11.4m people are 65 or over.

Reform UK leader Nigel Farage said younger voters were increasingly turning to his party, even though he did not support lowering the voting age. He said: “It’s an attempt to rig the political system but we intend to give them a nasty surprise.”

Even younger people feel 16 is too early to vote, polling suggested. A survey by Merlin Strategy for ITV News found 49% of 16 and 17-year-old said the voting age should not be lowered.

Cutting the voting age was a pledge in Labour’s general election manifesto and 16-year-olds can already take part in elections for the Scottish Parliament and Welsh Assembly.

Conservatives accused Labour of rushing the announcement. Paul Holmes, Shadow Communities Minister, said: “Labour’s rushed announcement today that they have announced in an attempt to avoid parliamentary scrutiny and without consultation is a confusing message to young people.

“Sixteen-year-olds will be able to vote in an election but not stand as candidates, and they will be able to vote but not permitted to buy a lottery ticket, consume alcohol, marry, or go to war. This is a hopelessly confusing policy from Labour, who appear uncertain themselves about what they want young people to be allowed to do.”

However Liberal Democrats and the Green Party backed the change. Lib Dem Cabinet Office spokesperson Sarah Olney MP said: “Votes at 16 is a no-brainer. Liberal Democrats have campaigned for this change for well over twenty years and so of course we welcome this decision.”

Green Party MP Ellie Chowns said: “Giving 16- and 17-year-olds the vote is a long-overdue step towards a stronger, more inclusive democracy. Young people have powerful voices and a vital stake in decisions about their future — it’s only right that they have a say at the ballot box.”

A lower voting age was also backed by children’s campaign group the NSPCC and headteacher’s union the NAHT. Paul Whiteman, NAHT general secretary, said: “A wide range of political decisions affect 16 and 17-year-olds, whether they be continuing their education, or entering training or employment – from changes to further education courses and university fees, to tax rates, housing policy, and public transport. “

Harry Quilter-Pinner, executive director of the IPPR think tank, said the changes were “is a vital step toward rebuilding confidence, modernising our institutions, and pushing back against the rise of populism.”

In other measures announced by Ms Rayner, the Government will introduce tougher punishments for people who abuse politicians and election candidates, following concerns about the level of harassment during the last general election, when some Labour MPs were targeted by campaigners opposed to the war in Gaza.

There will be a move towards automatic voter registration, so that people no longer need to fill in an electoral registration form to be able to vote.

The Government has rejected calls to scrap restrictions introduced by the Conservatives that required people to show ID in order to be able to vote. But the rules will be loosened so that bank cards count as a form of identification, while under the current arrangements only certain types of photo ID were accepted.

Legislation will also crack down on what it says are concerns about foreign donors influencing UK politics by providing funding via “shell companies”.

Ms Rayner said: “For too long public trust in our democracy has been damaged and faith in our institutions has been allowed to decline.

“We are taking action to break down barriers to participation that will ensure more people have the opportunity to engage in UK democracy, supporting our Plan for Change, and delivering on our manifesto commitment to give sixteen year olds the right to vote.”

But she was left red-faced after writing in the Times that people can get married at 16 in England – when in fact the age was raised to 18 in 2023.