The social network received the massive sum from a mystery organisation called Mainstream Network whose adverts urged voters to write to their MPs demanding they “chuck Chequers”. The slogan became part of the Brexit vocabulary after Boris Johnson launched a scathing attack on the Prime Minister’s strategy after she seemed to have secured full Cabinet support at her Buckinghamshire retreat last summer. Mr Johnson resigned the followed then Brexit secretary David Davis in resigning over the plan just days later after it was agreed on July 8, 2018.
Eleven million people saw the Mainstream Network adverts over the following 10 months.
A House of Commons committee launched a full investigation into Facebook’s involvement in the campaign and demanded they come clean about who paid for it.
Facebook vice president Richard Allan wrote to Damian Collins, chair of the Commons’ culture committee, saying the information was confidential but the social media giant had disclosed it to the information commissioner.
In his letter, Mr Allan wrote: “Facebook has provided information to the information commissioner’s office (ICO) on a private and confidential basis.
“It is now a matter for ICO, acting in accordance with its statutory duties, to determine what they will do with the data provided to them.”
The information commissioner, Elizabeth Denham, has agreed to include the committee’s demand to help her investigation into how social media firms can be manipulated by external political forces.
Mr Collins told The Sun it was imperative voters knew who was targeting their social media feeds with political adverts.
The Conservative MP for Folkestone and Hythe said: “I believe there is a strong public interest in understanding who is behind the Mainstream Network, and that this information should be published.
“People should have a right to know who is targeting them with political advertisements and why.
“That is why the committee had called for a change in the law to outlaw these kind of dark adverts from secret campaigns.”
The Chequers plan laid out the future relationship Mrs May wanted to pursue with the European Union in Brexit negotiations.
Brexiteer Dominic Raab, who served as Brexit secretary after Mr Davis until resigning in protest at the draft Withdrawal Agreement in November, described Chequers as a “principled and pragmatic plan for the relationship that we wish to build for the future”.
Unveiling the plan to the House of Commons, Mr Raab added it proposed “a free trade area for goods to maintain frictionless trade, supported by a common rulebook and a new facilitated customs arrangement.”
The Chequers plan was roundly rejected by the European Union in the following September.
Brussels’s chief Brexit negotiator Michel Barnier questioned whether it breached the integrity of the single market and said Britain could not go about “cherry picking” such elements of the EU.