Lawyers for the campaigner Gina Miller have made an urgent application to the high court for a judicial review of Boris Johnson’s plan to prorogue parliament, in the first shot in what will be an intense battle in the coming days to torpedo the prime minister’s plan.

“This is a brazen attempt, of truly historical magnitude, to prevent the executive being held accountable for its conduct before parliament,” said Miller, who first rose to prominence in 2016 when she brought a legal case that forced parliament to legislate before article 50 could be invoked.

And in a separate legal challenge, lawyers seeking to reverse the move to prorogue parliament hope a Scottish court will speed up its process of deciding whether the measure is unconstitutional and illegal, making its decision early next week.

Miller said she had received legal correspondence from government legal officers in the last two weeks stating that the issue of prorogation was of no more than “academic” interest. She said this now proved that Johnson has misled the nation.

She said in a statement issued on Wednesday night: “It is, sadly, all too clear from today’s announcements, that prorogation is a desperate reality, not a mere theoretical nicety. In view of this, I urge our courts to urgently hear my application for judicial review before 9 September 2019 – the earliest date that prorogation of parliament could come into effect.”

“We have all been comprehensively misled by the prime minister and his lawyers. A reply from the government legal department received late on 27 August stated: ‘The proposed intention to bring legal proceedings in respect of events which have not occurred and may never do so is noted. For the avoidance of doubt, we do not accept that the approach taken in your letter is an appropriate one.’

“To put this in an official legal letter and send it out at the same time as you are drafting a press release confirming parliament’s suspension the following morning illustrates just how manipulative and anti-democratic this prime minister and his government really are.”

Play Video Nationwide protests as Boris Johnson suspends parliament – video

Meanwhile, lawyers acting for the Scottish National party’s Joanna Cherry and 74 other MPs and peers expect to be in court in Edinburgh this Friday morning to urge Scotland’s civil court, the court of session, to block the suspension of parliament.

They had already won approval for a full hearing on Friday 6 September of their legal challenge to Johnson’s proroguing strategy, but will now ask the court to hear the case early next week.

Jolyon Maugham QC, the anti-Brexit lawyer who helped coordinate the legal challenge through his Good Law Project, said they believe the courts would be able to reverse the decision even though it had been approved by the Queen.

Jo Maugham QC (@JolyonMaugham) We believe Parliament can be unsuspended - and will be asking the Court of Session to do exactly that either tomorrow or on Friday. https://t.co/hIGF2awNjE

The MPs’ lawyer, Aidan O’Neill QC, is expected to attack what Johnson and the privy council asked the Queen to do earlier on Wednesday, rather than the Queen’s decision to approve it.

O’Neill will argue the court can order UK ministers to request the Queen reverses the prorogument, again via the privy council. Both sides are likely to immediately appeal the judge’s decision, whichever way it goes, leading to a series of urgent court hearings likely to end up at the UK supreme court.