The European Research Group (ERG) is a research support group and caucus of Eurosceptic Conservative Members of Parliament of the United Kingdom. The journalist Sebastian Payne described it in the Financial Times as "the most influential [research group] in recent political history".
Serving an annual average of 21 MPs including cabinet members, the group's focus is the single issue of the UK's withdrawal from the European Union.

History
Origins and Pre-EU referendum, 1993–2016
In July 1993 Sir Michael Spicer, the then MP for West Worcestershire, created the European Research Group in response to growing concerns about Britain's continued integration into the European Community through the Maastricht Treaty. The Eurosceptic group, which was chaired by Spicer, aimed to promote coordination of right-of-centre opposition across Europe and worked alongside other anti-EU groups such as UKIP and the Referendum Party. Support for the group was boosted in 1995 after it published an anti-federalist pamphlet discussing Euroscepticism which included a foreword by Prime Minister John Major.

Contributors to the research output of the ERG have included Daniel Hannan and Mark Reckless who wrote a paper 'The Euro: bad for business' and Hannan acted as the ERG's first secretary in 1993 according to The Guardian.

An unexpected consequence of the creation of the Independent Parliamentary Standards Authority (IPSA), under the Parliamentary Standards Act 2009 and in response to the parliamentary expenses scandal of 2009, was the formation of a sustainable revenue stream for the ERG through the formal mechanism of IPSA's administration of MP's subscriptions to pooled services. This created an opportunity for the ERG, an unincorporated association with no obligation to publish accounts, to fund researchers and establish a social media communications network at taxpayer's expense.
Senior researchers have included Robert Broadhurst, Conservative Parliamentary Researcher of the Year 2010 in the Dods Parliamentary researcher awards, and Christopher Howarth, formerly of Open Europe and son of ERG subscriber Gerald Howarth, who succeeded Broadhurst. In November 2016, Howarth represented the ERG at the parliamentary researchers' and academics' conference on Brexit He is a regular contributor to ConservativeHome and City A.M..
In the period leading up to the EU referendum ten members of ERG acted in an official capacity for Vote Leave:
Since the Brexit referendum
Following the result of the Brexit referendum in 2016 Chris Heaton-Harris MP resigned as ERG's chair and the new chair Steve Baker and deputy chair Michael Tomlinson announced a relaunch of the ERG, calling for the government to withdraw from the European Economic Area (EEA) and the European Union Customs Union. Baker was subsequently promoted to Parliamentary Under-Secretary of State for Exiting the European Union and in May 2017 Suella Braverman replaced him as the group's chair. In January 2018, Braverman was also promoted to the Department for Exiting the European Union as Parliamentary Under-Secretary of State making way for Jacob Rees-Mogg to be elected.
On 11 September 2018, members of the ERG met in Westminster to discuss plans to bring down the then prime minister, Theresa May.
On 4 February 2018, columnist Peter Wilby was highly critical, writing that "The highly secretive body seems to devote most of its efforts to what, if it were left-wing, would be called plotting." In the same article, he quotes The Times as saying it is "the most aggressive and successful political cadre in Britain today".
On 15 February 2019, the Press Association reported that "Critics, however, accuse it of acting as a “party within a party”, running its own whipping operation in support of its objective of a so-called “hard” Brexit, if necessary leaving without any deal with Brussels."
On 26 July 2018, the German public international broadcaster Deutsche Welle reported that "The European Research Group is a lobbying entity pushing for a no-nonsense, hard Brexit. Some say it is essentially running the show, not the British government." and "In February 2017, the group sent a letter to May setting out their hard-line Brexit demands: Britain should not only leave the EU but also the single market and customs union. That prompted Conservative MP Nicky Morgan, who voted remain, to accuse the ERG of holding Theresa May to ransom. Her then colleague Anna Soubry said that Jacob Rees-Mogg was "running our country. Theresa May is no longer in charge."





