Barbara Waterman was born 13 years after the Representation of the People Act gave women over 30 the right to vote in 1918. But it was not until three years ago, in the 2015 election, at the age of 83, that she finally used that right. Until then, Waterman thought she was barred because of her learning disability.

Her belief that universal suffrage didn’t extend to people such as her is not uncommon, according to Dimensions, a charity that runs a scheme to help and encourage people with learning disabilities and autism to vote. What changed for Waterman was that she became involved in the charity’s Love Your Vote scheme. It gave her a “voting passport”: a document that provides instructions for polling station staff regarding how she would like to be assisted to vote. After studying Easy Read manifestos produced by each of the political parties online, Waterman was supported to cast her vote for the first time in 2015, then again in June 2017.

“The voting passport helped me remember what to do when I got to the place where you vote,” says Waterman.

While, legally, universal suffrage has been achieved for all undetained citizens over the age of 18, many people still find it difficult to vote in elections. Ciara Lawrence, campaigns officer at the learning disability charity, Mencap – who has a learning disability herself – says: “Even today some people still question whether we have capacity or can make decisions on who to vote for. This is insulting and wrong. We have a right to vote like anyone else, but still face huge barriers.”

People with physical disabilities can face problems voting, with 67% of polling stations not being accessible. And blind or partially sighted people are often hindered in their attempts to even make it on to the electoral roll by registration forms that are not easy to read.

One hundred years this week after women got the vote, there are fears that proposals to introduce photo ID checks at polling stations could further disenfranchise millions, including disabled or homeless people, older voters and the poorest citizens.

Cat Smith, Labour’s shadow minister for voter engagement, has flagged various problems with the proposals. Trials in May’s local elections in five towns in England – Woking, Gosport, Bromley, Watford and Swindon – will require passports or driving licences to be shown at some polling stations, and polling cards in others. Smith says concerns have been raised by disability charities about these trials. “Disabled people are less likely to have driving licences, and polling cards, which will be required in some areas, are hard to recognise for a blind person as they feel the same as many pieces of junk mail.”

A polling station in the 2017 general election Photograph: Andrew Matthews/PA

The cost of passports and driving licences is prohibitive for some, at a minimum of £34 for a provisional driving licence and £72 for a passport, and will be a barrier to voting for the poorest people if free provision of ID is not introduced. Although Northern Ireland has required voter ID since 1985 in a bid to stamp out widespread electoral fraud, it issues free photographic ID cards to voters.

“Voter personation is a serious offence, and there is no doubt that cuts to our police make this more difficult for them to investigate and seek prosecutions However, due to the small number of proven cases [of fraud] and the consequences of voters being put off voting after being required to show ID, the government is taking a sledgehammer to crack a nut in this case,” says Smith.

Older people, too, are less likely to have driving licences or passports. A Labour analysis of the five towns taking part in the ID trials found that at least 10,000 people aged 65 or over are unlikely to have this type of approved photo ID. Data from the 2011 census shows that only 46% of people over 85 hold a passport and 50% of women over 70 do not have a driving licence.

For homeless and formerly homeless people, losing their ID and then having to apply for and afford new ID is insurmountably difficult. Maeve McGoldrick, head of policy and campaigns at homelessness charity Crisis, says: “Registering to vote can already be a complicated process for homeless people, but, with the right forms and guidance, anyone who has the right to vote in this country can do so – with or without a permanent address. Making it compulsory to show identification before voting risks compromising a basic human right by creating further barriers for people who may no longer have an acceptable form of ID, thanks to the often unpredictable and chaotic lifestyle homelessness can cause.

Without a place to call home and somewhere to keep documents, many of our clients struggle to keep hold of identification, and already struggle to claim benefits, access healthcare or open a bank account as a result. We would welcome the opportunity to work with government to identify the solutions before these changes come into force.”

In December, the government published a five-year democratic engagement plan designed to ensure that everyone eligible to register to vote is given the opportunity to do so. It sought to identify the needs of under-registered groups and to work with organisations to make it easier for these groups to exercise their democractic rights. Chris Skidmore, the then minister for the constitution, said: “The government believes that fostering democratic participation must start with an understanding of the barriers that prevent individuals and communities form registering to vote.”

But Darren Hughes, chief executive of the Electoral Reform Society, is sceptical that making people show ID will help. “Forcing voters to bring photo ID to the polling station is counterproductive,” he says. “Its real impact would be to add an additional barrier to those wishing to cast a legitimate vote. There are millions of people who don’t hold either a passport or a driving licence: mandatory voter ID – with no free provision – would stop those people from exercising their right to vote.”

The issue of what happens on polling day for those who do have ID is also an issue. “What about voters who simply forget their ID and then don’t return to vote?” Hughes asks. “Are we really going to disenfranchise honest voters to placate those who claim there is fraud, when there’s no evidence it’s a major problemin the UK?”

The gap between voting intention and actual participation still remains particularly high among people with disabilities. Only 31% of people with a learning disability reported that they voted in the 2001 election, in comparison with 59.4% of the general population, and research by Mencap found that while 70% of people with a learning disability say they intended to vote in the 2015 general election, 60% said they found the process of registering to vote too difficult, and 17% said they had been turned away from a polling station. Many charities cannot see voter participation increasing if voter ID is rolled out without addressing disability rights.

As Waterman says: “It is really important to vote, and if you have the right to vote you really should as it is your way of saying what you want to happen about your country.” And Lawrence is clear what should be done. “All political parties should be making adjustments so people with learning disabilities are included and have a voice in politics. But at the moment we can still feel excluded and not fully part of society.”

A Cabinet Office spokeswoman says: “We are committed to ensuring everyone who is eligible to vote can vote. If voters do not have the required ID then councils provide alternative methods for voters to identify themselves. We already ask that people prove who they are to collect a parcel from the post office, rent a car, secure a mortgage, or travel abroad – and we should take the same approach to protect voting rights.”