Mishcon de Reya is acting for Leave.EU on its appeal against the Electoral Commission's £70,000 fine for offences relating to campaign funding and spending during the referendum campaign.

The commission's fine came after it found the Brexit campaigning group inaccurately filed three loans received during the campaign and failed to include at least £77,380 in its spending return, thereby exceeding its spending limit.

Leave.EU co-founder Arron Banks (pictured above right), who appeared in front of the Digital, Culture, Media and Sport Committee's inquiry into 'fake news' this morning (12 June), told the committee that the appeal was filed at 9am today.

In a statement, the organisation said: "Leave.EU is striking back at the scheming Electoral Commission lying at the centre of the anti-Brexit campaign. [...] We look forward to seeing their representatives in Court. Brexit will not be beaten, and neither will Leave.EU."

The news comes as journalism website Byline has instructed London law firm Bindmans to serve Banks and former Leave.EU communications director Andy Wigmore (pictured above left) with a defamation notice, after an online dispute over the source of news revelations in this weekend's Sunday Times about Banks' Russian connections.

Banks has alleged on Twitter that articles published this weekend, which revealed previously undisclosed meetings with the Russian ambassador to the UK, had made their way into the press after journalist Isabel Oakeshott – who had been given the emails to ghostwrite Banks' book about the Brexit campaign – had been hacked by Byline and The Guardian.

On Sunday, Banks tweeted to Guardian and Observer writer Carol Cadwalladr: "The @thetimes have already got your story, you obtained from emails stolen from @IsabelOakeshott."

Banks also tweeted that Oakeshott had told him that his emails "were hacked by Byline/@guardian and that you were using stolen information".

Replying to Banks' tweet, Wigmore replied "theft is equally criminal", tagging Mishcon de Reya's official Twitter account in the tweet. Wigmore also referenced Mishcon in a tweet in which he referred to getting "quite an education" on theft of data and GDPR by "wonderful solicitors @Mishcon_de_Reya".

Bindman's letter to the pair states that their tweets "bear the defamatory meaning" that Byline hacked Oakeshott's email account. Byline has asked for a retraction and damages.

Mishcon was contacted for comment.