One former Conservative cabinet minister has called it an “illiberal solution for a non-existent problem”.

The government says making people prove their identity before they vote will help to “combat the inexcusable potential for voter fraud in our current system and to strengthen the integrity of our elections”.

What is the problem?

In most of the UK, you don’t have to show identification or even a polling card in order to vote in an election.

It’s different in Northern Ireland, thanks to historic fears of widespread electoral fraud.

The law was changed in 2002 to make photo IDs mandatory at polling stations in Northern Ireland.

The UK government’s Electoral Integrity Bill would bring the rest of Britain in line with Northern Ireland. It would also answer calls from the Electoral Commission for tighter rules on voter ID.

International observers from the Organization for Security and Co-operation in Europe have recommended several times that voters should be required to show ID before being given a ballot paper in British elections.

How much voter fraud is there?

Not having to show ID creates an obvious theoretical risk of “personation” – people pretending to be someone else in order to steal their vote. But there is no evidence that this is a widespread problem in the UK.

This is why many campaigners are accusing the government of trying to fix a problem that doesn’t exist.

Convictions for the crime of “personation” at polling stations are vanishingly rare. The Electoral Commission recorded one conviction in 2017 and none at all in 2018, for example.

The government tends to focus on the potential for abuse rather than the numbers of cases prosecuted.

In 2016 the former Conservative cabinet minister Lord Pickles published a report into electoral fraud, saying: “Despite the low numbers of allegations and rare cases of personation being prosecuted, there is a concern that the absence of evidence does not mean this practice is not taking place.

“And even if it is not, there is a precautionary principle that comes into play in terms of the potential for it to happen.”

The Electoral Commission told FactCheck: “The UK has very low levels of proven electoral fraud, but we know from our public opinion survey work that it is an issue that concerns some voters.

“66 per cent of people say they would feel more confident in the voting process if there were a requirement to show identification.”

Why so much anger?

Civil society groups have variously suggested that the move will make it harder to vote for people who are young, gay, transgender, from an ethnic minority, homeless, living in rented accommodation, poor or working class, as these people are less likely to have a photo ID, particularly a driving licence or passport.

It’s been widely reported that as many as 3.5 million people in Britain don’t have any form of photo ID, but the truth is slightly more complicated.

This figure was calculated by the Electoral Commission in 2015 (here – page 18) and hasn’t been updated since then.

The commission drew up a list of types of photo ID it considered might be acceptable under a voter ID scheme, and the number they calculated depended on what was included on the list.

It included military ID cards, for example, but not student cards or bus passes issued by councils.

We won’t know the real number of people without ID until the government sets out more detail on which forms of ID will be accepted at polling booths.

Evidence from pilots

Pilots were held across 15 local authorities in 2018 and 2019. Voters had to show some form of ID before getting a ballot paper.

Both sides claim that evidence from the pilots supports their case.

Critics of voter ID say dozens or in some cases hundreds of voters were turned away from polling stations for not having a valid form of identification and did not return.

No demographic information was collected on these people who did not get to vote, so we don’t know if any particular group was disproportionately affected.

The government claims the results of the pilots show that requiring ID does not appear to significantly affect turnout.

In all the pilot areas, less than 1 per cent of voters did not get to vote due to lack of ID. So more than 99 per cent of people managed to follow the trialled rules on producing identification.

Will you get a free ID document?

There’s nothing preventing the government from acting to reduce the number of people who don’t have any kind of photo ID.

That’s what happened in Northern Ireland: voters who didn’t have the right documents could apply for a free photographic electoral ID card from their local council.

This went some way to answering the objection that people who could not afford the application fee for a driving licence or passport might be priced out of voting.

When the government first announced this bill in the Queen’s Speech in 2019, it explicitly said it would follow the Northern Ireland model, saying: “Any voter who does not have an approved form of ID will be able to apply, free of charge, for a local electoral identity document.”

This assurance is missing from the notes that accompany the 2021 Queen’s Speech, and we haven’t been able to pin the government down on whether they still plan to offer free ID cards to people who don’t have them.

On the question of funding, a government spokesman simply told us: “We will set out detail in due course.”

Will this help the Conservatives?

We know that ownership of certain forms of ID varies between demographic groups.

Black, Asian and mixed-race people are less likely to have a full driving licence than white Britons, for example.

At the last general election, Labour performed better than the Conservatives among younger voters and people from ethnic minority backgrounds.

It seems reasonable to predict that if you make it harder for large numbers of people to vote, and those people are disproportionately young and non-white, you will hurt Labour’s chances and favour the Conservatives.

But we haven’t seen a definitive piece of analysis that nails this point.

Boris Johnson was asked whether the scheme was an attempt to suppress votes for the Conservatives’ opponents at a press conference this week.

He said: “I would say that was complete nonsense and what we want to do is to protect democracy, the transparency and the integrity of the electoral process, and I don’t think it’s unreasonable to ask first-time voters to produce some evidence of identity.”

Wasn’t Boris Johnson against ID cards?

Lots of commentators have found footage of Boris Johnson railing against Labour’s plans to bring in ID cards.

Back in 2004, Mr Johnson said in print and in person that he would eat an ID card rather than being forced to carry one. Now the Prime Minister is asking people to show ID before they vote.

In fairness to him, Labour’s 2004 scheme for a universal, compulsory ID card was fundamentally different to the current government’s plans.

The Labour Home Secretary David Blunkett wanted a new biometric ID card that would eventually be mandatory, with personal data from the cards stored on a government database.

Mr Johnson’s bill is not based on a new kind of photocard and a government spokesman told us: “This is not a move towards compulsory ID cards.”