Members of the official Brexit campaign during the EU referendum may have committed criminal offences relating to overspending and collusion, according to lawyers advising whistleblowers who worked inside the organisation.

Clare Montgomery and Helen Mountfield, barristers from Matrix chambers, concluded in a formal opinion that there was a “prima facie case” that Vote Leave submitted an inaccurate spending return and colluded with BeLeave, which was aimed at students.

They were reviewing a dossier of evidence supplied by solicitors Bindmans, which contained examples of alleged collusion showing that Vote Leave and BeLeave were not separate and therefore that the leave campaign spent over the £7m legal limit set by the Electoral Commission.

MPs will debate the allegations in the Commons on Tuesday, after the Lib Dems secured an emergency debate. The dossier has also been passed to the Electoral Commission, which is responsible for election law.



Tamsin Allen, from Bindmans, told a press conference “that there is a strong suspicion that the campaigns were very closely linked and co-ordinated, in which case it may be that Vote Leave spent huge sums unlawfully and its declaration of expenses is incorrect”.

Vote Leave formally declared it had spent £6.77m during the campaign in the summer of 2016, well below the £7m limit. That figure, however, excluded £625,000 donated by Vote Leave to BeLeave which was spent on the same digital marketing company, AggregateIQ, that Vote Leave used.

Vote Leave, whose leading members include Boris Johnson and Michael Gove, strongly denies any coordination with another campaign group during the referendum.

But Allen said there were grounds to suspect Dominic Cummings, Vote Leave’s campaign director, “of having conspired to break the law” because he was among those engaged in discussions with BeLeave about their organisation, activity and funding.

Emails compiled by Bindmans appear to show that Vote Leave assisted in the creation of BeLeave’s branding and that there was constant communication between to the two groups, who were based in the same office. They suggest that they used a single shared drive where campaign materials were shared.

Bindmans’ dossier was largely based on evidence supplied by Shahmir Sanni, a volunteer who worked at both Vote Leave and BeLeave, with supporting evidence from Christopher Wylie, a former employee of the political consultancy firm Cambridge Analytica who worked on the Trump election campaign and who had worked for AggregateIQ.

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A Facebook chat records Sanni discussing with the BeLeave founder, Darren Grimes, how they might set up independently in May 2016. “We could just say that you and I will be handling the money and using our social media data (alongside VL data) to decide where best to spend our money,” Sanni wrote.

Wylie said that an employee of AggregateIQ had told him the relationship between Vote Leave and BeLeave was “totally illegal” because “you are not allowed to coordinate between different campaigns and not declare it”. He said “I don’t feel confident in the result [of the referendum]” as a result.

The lawyers said there were also “grounds to investigate” Stephen Parkinson, Vote Leave’s national organiser, who now works as Theresa May’s special adviser and Cleo Watson, who was Vote Leave’s head of outreach and also now works at No 10. Parkinson and Watson have denied any wrongdoing.

Montgomery and Mountfield said in their opinion that there were “significant questions” about the role of a senior Vote Leave official who appeared to have removed references to themself and others in discussions with BeLeave after the referendum by appearing “to change permissions on a BeLeave shared drive in March 2017 while an EC [Electoral Commission] investigation into Vote Leave was under way”. This revoked permission for the official, Cummings and a third person from having access to BeLeave materials.

Separately, it emerged that AggregateIQ has worked in the United States developing software for Cambridge Analytica, which has been accused of benefiting from the harvesting of 50m Facebook profiles to use in political targeting. The little-known AggregateIQ helped develop software used by senator Ted Cruz in his failed presidential bid, Gizmodo reported, cited coding documents found online. Previously the only links noted were a licensing agreement and Wylie’s claim that he helped set up AggregateIQ.

Cummings wrote in a blogpost before the press conference that “a team will also be putting in formal complaints to the EC and ICO [Information Commissioner’s Office] about the illegal conduct of the remain campaign”. He has previously argued that Stronger In also took advantage of loopholes to reduce the expenditure against its £7m limit.

Vote Leave has repeatedly denied it coordinated its activities with BeLeave. Venner Shipley, Vote Leave’s lawyers, said: “We have never been instructed by, nor have we ever provided advice to BeLeave.”

The allegations have all been denied by Vote Leave and its former officials, who reject all accusations of wrongdoing.

The Electoral Commission has already assessed the issue twice and found in favour of Vote Leave on both occasions. But a judicial review launched by the Good Law Project in November led to the commission re-opening an investigation into the donation which is yet to report its findings.