• Politicians have uncovered evidence of a dark advertising campaign on Facebook, in which Brits were encouraged to lobby against Prime Minister Theresa May’s Brexit plan.
• The Digital, Culture, Media, and Sport Committee said £257,000 was spent on the adverts by an anonymous group called the Mainstream Network.
• The committee wants Facebook to reveal who is behind the campaign after it released its new political ad transparency tools in the UK this week.

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An influential group of politicians has uncovered evidence of a dark advertising campaign on Facebook, in which users were encouraged to lobby against Prime Minister Theresa May’s Brexit plan.

In findings published on Saturday, the Digital, Culture, Media, and Sport Committee said an anonymous organisation called Mainstream Network spent £257,000 ($US335,148) on ads that reached up to 11 million people over a 10-month period.

The “sophisticated” campaign included a direct call to action for users to email their MP asking them to “chuck Chequers,” short-hand for May’s controversial Brexit negotiating position agreed at her Chequers retreat in July.

Mainstream Network has no known named organisation, UK address, or individual associated with it, the Digital, Culture, Media, and Sport Committee said.

“Here we have an example of a clearly sophisticated organisation spending lots of money on a political campaign, and we have absolutely no idea who is behind it. The only people who know who is paying for these adverts is Facebook,” said the committee’s chairman Damian Collins.

It’s the kind of activity that could be made public with Facebook’s new political ad transparency tools, which were launched in the UK this week. But they have come too late to capture the Mainstream Network campaign, and a committee chairman said Facebook should release details of who is behind the adverts independently.

In a statement, Facebook did not address whether it would voluntarily release details about who is behind Mainstream Network.

“On November 7, all advertisers will have new requirements before they can place political ads in the UK, including Mainstream Network. These advertisers will need to confirm their identity and location through an authorisations process and accurately represent the organisation or person paying for the ad in a disclaimer,” said Rob Leathern, director of product management.

“These steps must happen or the advertiser will be prevented from running ads related to politics on Facebook. We know we can’t prevent election interference alone and offering more ad transparency allows journalists, researchers and other interested parties to raise important questions.”

The Digital, Culture, Media, and Sport Committee uncovered the Mainstream Network with help from communications agency 89up.

Users were targeted with localised ads which clicked through to the Mainstream Network website, 89up said, where they were encouraged to submit a pre-written email to their local MP. The email calls on the MP to “bin the Chequers Deal before it’s too late.”

Collins and Paul Farrelly, another lawmaker on the committee, were among many MPs whose constituents were targeted. Mainstream Network also carried a number of pro-Brexit news stories on its site, which have had more than 140,000 social media engagements, according to 89up.

The company also said Mainstream Network could be in breach of the EU’s new GDPR privacy laws. This is because whenever a user emails their MP from the site, Mainstream’s own address is copied, meaning that the user’s email address could potentially be being stored by the organisation.

Collins said: “Facebook has recently announced a set of changes to increase transparency around political advertising on its platform. This example offers Facebook an opportunity to show it is committed to making that change happen – if you are targeted with a message or asked to do lobby your MP, you should know exactly who is behind the organisation asking you to do it.”

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