Nadine Dorries has been reported to the chief whip and Commons speaker after allegedly sending “forceful” emails to the government about not being given a peerage. In a highly unusual move, the cabinet secretary, Simon Case, revealed he had “flagged” the issue to the parliamentary authorities, and also asked for advice about any potential breach of the law. The revelation threatens to reignite questions over Boris Johnson’s honours list, which was published last month but did not include at least one other MP who had expected to be given a peerage – leading that MP, Nigel Adams, to resign in protest. Dorries tweeted on 9 June that she was standing down “with immediate effect”, but more than a month later has not formally done so. She said recently she was waiting for answers from ministers about why she was denied a peerage. The Tory MP William Wragg described her as the “lingering” MP for Mid Bedfordshire, during an evidence session of the public administration and constitutional affairs committee on Wednesday. Dorries, according to Wragg, used “rather forceful communications … threatening to use her position as an MP to get to the bottom of why she hasn’t been given a peerage”. Case said he was “aware of those communications” and had “flagged them” to the chief whip, Simon Hart, and Commons speaker, Lindsay Hoyle. Wragg pressed him on whether Dorries’ messages potentially conflicted with the Honours (Prevention of Abuses) Act. The law was passed in 1925 after the cash-for-honours scandal involving the prime minister of the time, David Lloyd George. Only one person has ever been prosecuted under the act – Maundy Gregory, who was Lloyd George’s “honours broker”. The act, a simple, three-line clause piece of legislation, made it illegal to seek, accept or obtain honours in exchange for money or another gift. When Wragg asked Case if he had taken legal advice on whether the act “could come in to play”, the cabinet secretary said he had “taken initial advice but asked for more”. The prime minister, Rishi Sunak, was urged to remove the whip from Dorries. Daisy Cooper, the Liberal Democrats’ deputy leader, said: “These allegations are staggering and it’s crucial a swift investigation takes place into whether Nadine Dorries may have broken the law. Not only is Dorries failing to represent the people of Mid Bedfordshire, but now it emerges she has allegedly sent threatening messages to civil servants. “The least Rishi Sunak can do is suspend her by withdrawing the Conservative whip while any investigation takes place.” No 10 refused to comment on the challenge, saying it was a matter for the whips’ office. “In the broadest sense, we would always encourage people to communicate politely,” said Sunak’s spokesperson. Dorries was contacted for comment. She retains the Conservative whip, but continues to be a thorn in the side of the prime minister. The former culture secretary announced this week she was penning a book titled The Plot: The Political Assassination of Boris Johnson. It will be published days before the Conservative party conference in early autumn. The book, for which Dorries got a £20,500 advance from HarperCollins, is billed as the story of “treachery and deceit at the heart of the Westminster machine”. It is expected to hit the stands on 28 September, just three days before Tory activists and members convene for conference on 1 October. Dorries was among seven Tory MPs recently rebuked for trying to interfere in the privileges committee investigation of Johnson, which concluded he misled parliament over Partygate.