The Jeremy Corbyn-supporting group Momentum, an integral part of Labour's surprisingly successful reemergence in the last election, is being investigated by the Electoral Commission over potentially excessive spending during June's election.
According to numerous media reports, officials are assessing whether the grassroots campaign group broke spending rules, including supplying incomplete statements, invoices and a failure to disclose payments of more than £200.
Bob Posner, the Electoral Commission's Director of Political Finance and Regulation and Legal Counsel, told Sky News: "Momentum are a high-profile, active campaigning body.
"Questions over their compliance with the campaign finance rules at June's General Election risks causing harm to voters' confidence in elections.
"There is significant public interest in us investigating Momentum to establish the facts in this matter and whether there have been any offences.
"Once complete, the Commission will decide whether any breaches have occurred and, if so, what further action may be appropriate, in line with its enforcement policy."
Under UK law, non-party campaigners are limited to spending £31,980 in England; £3,540 in Scotland; £2,400 in Wales; and £1,080 in Northern Ireland over the course of a year.
According to Electoral Commission figures, Momentum spent £38,743.
Credited for creating a great deal of the hype surrounding Jeremy Corbyn's campaing, Momentum deployed thousands of activists and volunteers in key areas and fuelled the Absolute Boy's meme machine that spread across social media.
In response to the enquiry, Momentum, who claim to have 23,000 members and 200,000 "supporters" released a statement refuting claims of overspending.
"Our election campaign was delivered on a low budget because it tapped into the energy and enthusiasm of tens of thousands of volunteers across the country.
"Much of the Electoral Commission investigation refers to administrative errors that can be easily rectified.
"We have a good working relationship with the Electoral Commission, and will fully comply with the investigation going forward."
The internet, as usual, is split in its opinions of the case.
Watch this space.