A Labour MP has called for the suspension of Grant Shapps, the Conservative party chairman, because new evidence suggests that he held a second job for at least a year after being an MP.
John Mann, a Labour MP, called on the prime minister to "sack Grant Shapps as Minister without Portfolio".
For years, Shapps operated a business under the "Michael Green" pseudonym, posing as a millionaire web marketer.
Although the Tory chairman initially denied operating as Green, he eventually admitted using the pen name, saying it was not uncommon for MPs to use a separate business name.
Despite this, Shapps apparently threatened one of his constituents, a former Labour councillor, with legal action when the constituent claimed Shapps used the pseudonym.
According to documents seen by The Guardian, lawyers for Shapps forced the constituent to post a Facebook status explicitly making clear that Shapps has never lied using about the pen name while an MP.
The apology was to say: "Mr Shapps MP has at no time misled over the use of a pen name. Indeed, I now understand that he openly published his full name alongside business publications making it clear that he used a pen name merely to separate business and politics, prior to entering parliament."
Meanwhile, Tory MPs have rushed to Shapps's defence, arguing that Labour is "anti-business" for criticising him.
A statement from the Conservative party said: "Like many authors and journalists, Grant wrote with a pen name. This was completely transparent: His full name and biographical details were permanently published on the company's main website.
"Given that this was a decade ago, and was mentioned during the cut and thrust of an interview, he referenced that his writing career had ended when he became an MP: In fact it ended shortly afterwards."
Siraj Datoo is a political reporter for BuzzFeed News and is based in London.
Contact Siraj Datoo at firstname.lastname@example.org.
Got a confidential tip? Submit it here.