Nadine Dorries has been among the Tories’ punchiest advocates of a “hard” Brexit – arguing for Philip Hammond to be sacked, calling Dominic Grieve "treacherous", and telling colleagues lobbying for a soft departure from the European Union that they deserve to lose their seats.
But WhatsApp messages seen by BuzzFeed News reveal that Dorries needed to be convinced by colleagues about one of the eurosceptics’ firmest red lines: that Britain must withdraw from the customs union when it leaves the European Union in 2019.
As the Brexit talks reached a critical stage in October, Dorries messaged fellow Tory MPs in the European Research Group questioning one of the influential Brexit-backing group's articles of faith. "Is there any reason why, if countries outside of the EU are in the CU, we can't remain in the CU going forward?" the MP for Mid Bedfordshire wrote at 7:28am on 10 October last year.
Kemi Badenoch, one of the Tories' rising stars, replied minutes later, reminding Dorries of the ERG's position: Britain won’t be free to strike its own trade deals with countries such as the US unless it withdraws fully from the EU’s customs union.
"But, other countries who are members of the CU do," Dorries replied. "That's why I asked. Do they have exceptions? This was a question in a discussion last night. I need to find out what countries are members and have free trade agreements with other countries first."
As part of the customs union, the EU's 28 member states act as a single trade bloc, exchanging goods without internal barriers and negotiating deals with non-EU countries as one. None negotiate their own trade deals.
Dorries asked Christopher Howarth, the ERG's researcher, to get back to her with an answer to her questions. He and other members of the group responded with explanations of how the customs union works and the arguments for the UK leaving it.
Dorries admitted she had been stumped in a conversation with a politics teacher and didn't know enough about the trading relationships of the customs union's members to argue the point. After her colleagues replied on WhatsApp with arguments for leaving the customs union, Dorries said: "You have just convinced me what my gut always knew – it is so complicated and convoluted, we must get the hell out."
Dorries didn't respond to requests for comment on Friday, but on Saturday morning she tweeted a picture of the Times newspaper and a message to Hammond urging him to "stop trying to confuse" the issue surrounding the customs union.
The leaked WhatsApp exchange raised eyebrows among colleagues at the time, since leaving the customs union had long been regarded by senior Leavers as essential to implementing their vision for Britain's future outside the EU.
Jacob Rees-Mogg, the ERG's new chairperson, emphasised this view in a speech on Thursday night in which he attacked the customs union as a "protection racket" that stifles free trade and increases prices for consumers.
Dorries questions were also, Tory colleagues said, at odds with her public zeal about the benefits of Brexit. Dorries – a dedicated supporter of Boris Johnson, the leading advocate of a hard Brexit in cabinet – has been uncompromising in her criticism of Conservative colleagues who want the UK to remain closely aligned to the EU after leaving.
In October, days before Dorries posted the message about the customs union, she called for the chancellor Hammond to be sacked because he wasn't enthusiastic enough about Brexit. It was a view that many on the right of the party shared, but only Dorries was bold enough to say it on TV.
Then, in December, Dorries called for colleagues who voted against the government’s EU withdrawal bill to be deselected and barred from standing for the Conservatives again. She accused former attorney general Grieve, the senior Tory who led the rebellion by former Remainers, of "treachery".
In other tweets in December, Dorries appeared to be back on message about the customs union, telling SNP leader Nicola Sturgeon: “If we stay in the single market and customs union, we haven’t left.”
Dorries is one of the best-known and most outspoken members of the ERG, a powerful bloc of Tory backbenchers, chaired by Rees-Mogg, who are pushing for a clean break from the EU after March 2019. Among the group's demands is that the UK leaves the single market and ends free movement of EU citizens.
The group has about 40 to 50 active members, BuzzFeed News understands, more than the hard-core Tory Remainers and enough to force a leadership contest.
Since the 2016 referendum, the ERG has quietly influenced 10 Downing Street by running a secretive and disciplined parliamentary operation, which uses WhatsApp to coordinate meetings and media appearances and to make sure that all of its members know the right "lines to take" on Brexit policy.
The ERG has so far largely been loyal to Theresa May. However, they are growing increasingly restless after the UK agreed to a series of concessions, including agreeing to pay the EU a “divorce bill” of around £40 billion. Over the next several weeks, as the fight about the future of the UK's relationship with the EU escalates, the ERG will be important players behind the scenes.
The customs union will be one of the main battlegrounds. Brexiteers fear that Remainers are trying to manoeuvre May into preserving the status quo, binding Britain to the EU indefinitely. However, their WhatsApp communications suggest that the ERG hasn't always been as united on policy or strategy as they appear to be, and that not all its members have been as steadfast in their commitment to the group's red lines as Rees-Mogg.