Gina Miller, the pro-Europe campaigner, is targeting voters with tailored Facebook advertising in dozens of Labour and Conservative seats. The financier’s campaign group, Best for Britain, which is seeking to boost the number of pro-remain MPs in the next parliament, is sending out different messages to different voters in seats from Aberdeen to Southampton.

It is the latest example of the increasingly sophisticated “digital ground war” being fought during the general election, which has already seen the Conservatives and Labour spending an estimated £140,000 a week on targeting voters directly through their Facebook feeds. Digital campaigning companies have claimed they can help campaigners tailor adverts to individuals depending on the trail of information they have left online, and Labour and the Conservatives are expected to spend up to £1m each on advertising on social media in the general election.

On Wednesday, the information commissioner, Elizabeth Denham, launched an investigation into the practice and warned that if parties sent political messages to people based on their individual data, they could be breaking the law. There is no suggestion that Miller’s campaign is doing so, but it is sending different adverts to different groups and there is evidence to suggest that it is changing messages depending on voters’ age.

Photograph: Best For Britain

In Darlington, where Labour’s pro-remain Jenny Chapman is standing to retain the seat, a 50-year-old voter received an advert which said: “Jeremy Corbyn is not going to be prime minister, so you can vote for your Labour candidate.”

In Southampton Itchen, where Brexit-supporting Royston Smith is standing for the Conservatives, a voter was told: “Theresa May is going to win anyway, but it’s important to limit her majority.”

The ads often use the same image of a smiling Gina Miller, but are given different messages. In Battersea, Oxford West, Portsmouth South and Preston, the message was: “Prevent an extreme Brexit. Make this the biggest tactical vote in British history.”

Ads sent to people aged 20 to 31 in Birmingham Yardley, Wimbledon and South West Norfolk showed a young woman saying: “It seems like they’re going to make the decision and tell us afterwards.”

A similar ad sent to a middle-aged person in Tynemouth showed a worried older woman with the caption: “I would just like open and honest information.”



Photograph: Best For Britain

The adverts emerged from a snapshot of Miller’s campaigning so far gathered from a sample of over 5,000 voters supplying data on political Facebook adverts to the monitoring organisation Who Targets Me. She sent 10 different messages to constituents in 17 Labour seats and 15 Tory seats. The data was analysed by the Bureau for Investigative Journalism. Who Targets Me currently has voters registered in 613 constituencies and wants more people to sign up.



Announcing her investigation into the use of data analytics for political purposes, Denham said: “If political campaigns or third-party companies are able to gather up very precise digital trails to then individually target people, that is an area [where] they are going to be outside the law.”

A spokesman for Best for Britain said: “A variety of messages are sent to potential voters, and we endeavour to measure engagement and refine messaging to maximise the impact of the various Best for Britain campaigns. We are fully aware of, and compliant with, the ICO’s concerns. We do not take anything for granted and want to ensure donors’ generosity is rewarded with the most efficient and effective activities we can undertake. We do not hold any personal information on individuals, unless they have specifically signed up as supporters of the Best for Britain campaign.”