The ministerial code also states that ministers’ meetings should be arranged through their departments, with officials present. The Vox meeting was organised not by DExEU but by the European Conservatives and Reformists (ECR), the European Parliament grouping which includes the Tory party.

Heaton-Harris was a leading figure in the pro-Brexit European Research Group, led by Tory MP Jacob Rees-Mogg, before becoming a Brexit minister in July 2018. He resigned in April, in opposition to Theresa May’s Brexit deal.

As well as Spanish voters and potential investors, Espinosa de los Montero met with Heaton-Harris and two other Tory MPs aligned with the ERG, Andrew Lewer and Scottish Tory Ross Thomson.

“We saw three, and all three were Brexiteers,” Espinosa de los Montero said. “It was the first time we ever met and it was a nice, general conversation, not very specific,” he said, adding that: “We like to establish relationships with parties such as the Conservatives, which I think is our natural ally in the UK.”

After a photograph of Thomson with Espinosa de los Montero was posted on Twitter, a Scottish Conservative spokesman said that “none of these meetings constitute an endorsement of any views Vox may hold.”

Last month, openDemocracy revealed that Vox is a central part of a network of far-right movements across Europe, backed by American and Russian ultraconservatives, and supported by an American political consultant linked to the Trump campaign.

"Absolute scandal"

The meeting between Vox and Heaton-Harris is not the first time that discussions involving a Brexit minister and the UK’s departure from the EU have not been recorded in government transparency data.

Last year, Buzzfeed revealed that another Brexit minister, Steve Baker, frequently met to discuss Brexit with Shanker Singham, a trade lobbyist now at the dark money-funded think tank the Institute of Economic Affairs (IEA). These meetings took place outside of office hours, away from the Brexit department and were not disclosed to the public.

openDemocracy also revealed that, as minister, Baker was present at a European Research Group gathering on ‘Reporting Brexit’ and had dinner with an Italian libertarian think tank linked to the IEA. DExEU said that Baker, who resigned in 2018, was present at both events in a personal capacity, and not as a government minister.

“The government’s own rules are clear that when ministers engage external stakeholders on issues relating to official business this should be recorded and made public. This is not an obligation they can escape by claiming the meeting was on party or private time. Withholding or failing to report this information only gives the impression of impropriety,” said Steve Goodrich, senior researcher office at Transparency International UK.

Liberal Democrat Tom Brake accused Heaton-Harris of “currying favour with Vox”.

“I will be writing to the prime minister to ask whether the government supports negotiating with Vox or did Minister Heaton-Harris break the ministerial code?” Brake said.

Matthew McGregor, campaigns director, HOPE not hate said: “It’s an absolute scandal that a Tory MP has been meeting with representatives of a far right party. This is a deeply worrying state of affairs and Mr Heaton-Harris and his officials should explain themselves immediately. It’s hard to imagine any sort of justification for a meeting with Spain’s far right party, particularly if it discussed any British government policy.”

openDemocracy asked DExEU if the department had a record of Heaton-Harris’s meeting with Vox, and if the department would be examining whether a breach of the ministerial code took place.

In response, a DExEU spokesperson said: “The then Parliamentary Under Secretary of State for Exiting the European Union Chris Heaton-Harris did not meet representatives of Vox in a ministerial capacity and DExEU was not involved in the meeting referenced in the article contained in your request.”

openDemocracy approached Chris Heaton-Harris for comment and has yet to receive a response.

Additional reporting by Belen Lobos.