Let’s be under no illusion about the game that Boris Johnson is playing – he is trying to sneak his reckless and destructive no-deal Brexit under the noses of our parliamentarians through dissolution rather than prorogation.

This conclusion emerges from the legal correspondence between my legal team and the government’s, in which they go to great lengths to put my mind at rest on the matter of prorogation.

“Parliament will be afforded the opportunity to scrutinise the terms of exit and hold the government to account on its Brexit policy,” the letter states. “Proroguing parliament and denying MPs their right to vote on the country’s trajectory at this crucial time would be contrary to specific articles of law.”

There is no reference to bringing back the withdrawal agreement (with or without a backstop). Instead there is a lengthy assessment of the legal footing of NIEFA – the Northern Ireland (Executive Formation) Act 2019. In short, the letter is legal flummery designed to conceal Johnson’s aim in relation to Brexit.

Unsaid in the letter, but streaming through it like shafts of light through a broken roof, Johnson’s plan of action – doubtless guided by the arch-Brexiter svengali Dominic Cummings – is clearly to call an election and dissolve parliament as soon as the beginning of next month, with polling at some point after the existing Brexit day of 31 October.

He is gambling everything on Jeremy Corbyn’s unpopularity and a public which, at that point, will have yet to experience the full force of no-deal economic headwinds. He may even hold a pre-Brexit budget to lull the public into a false sense of security, bribing them with their own money, through a splurge of new spending promises and tax cuts funded by an increase in the national debt.

Johnson is gambling everything on Jeremy Corbyn’s unpopularity

All of this amounts to a neat, if profoundly cynical and undemocratic, trick. While the prorogation of parliament happens at the end of every parliamentary session, dissolution occurs before an election. The difference between prorogation and dissolution is fundamental, not procedural, and the effects of dissolution would be profound for all of us.

Under the Fixed-term Parliaments Act 2011, parliament is automatically dissolved 25 days before an election, but it can be done sooner. Such an election lock would close the doors of parliament and legally push the UK over the EU exit date. So, while MPs debate a vote of no confidence and Corbyn attempts to become leader of a government of national unity, Johnson could dramatically pull the rug from underneath their feet.

Our unwritten constitution has always been based on the assumption that no one as unscrupulous as Johnson or his chief adviser would ever come to reside in 10 Downing Street, but that is what we now have to face up to. A general election on their terms and timetable would guarantee their sacred no-deal Brexit, and assure him five years in office in which to turn the UK into a laboratory for experimenting with the most extreme rightwing ideology we have ever seen.

Brexit is their cloak to disguise political ambitions to change our country. Surrounded by individuals set on putting a torch to the old order, they are using propaganda to set the people against parliament and create chaos out of which will emerge a survivalist economy.

Poll after poll has shown that a no-deal Brexit is emphatically not what the public wants – whatever the Leave campaign-staffed No 10 press office may tell lobby correspondents. For all Dominic Raab’s protests, it was never the way Brexit was sold in the referendum of 2016. And keep in mind these two statistics: Johnson came into office with his talk of “do or die” Brexit on the back of just 92,153 Tory members’ votes. By contrast, more than 6.1 million citizens have signed a petition calling for Article 50 to be revoked.

All is not, however, lost. The government normally controls the parliamentary timetable, but ultimately MPs have the power to make their own rules – and they should be preparing to take control immediately they get back from the summer recess. John Bercow, the Speaker, has already demonstrated that he is a steadfast servant of the House and not the government’s lapdog.

MPs should be preparing to take control immediately they get back from the summer recess

The two routes open to Johnson are as follows. He can cut and run if he thinks he can win an ensuing general election, but that requires him securing a two-thirds majority vote to get his general election dissolution. In that vote, MPs should make dissolution conditional upon an act of parliament requiring the prime minister to request an extension to Article 50 until the end of 2019. The EU has already made clear it would accede to this, not least because it would be in line with our constitutional requirements.

The second route: Johnson loses the confidence motion expected to be tabled by Labour at the start of September, banks on no one being able to form a new government (led either by him, another member of the parliamentary Conservative party, the leader of the official opposition, or some other national unity government figurehead), and, after 14 days, a general election is automatically triggered.

In their letter the government’s lawyers question my right to hold him to account. It perfectly betrays the profound arrogance of the man. It is of course one of the great joys of our country, a beacon of democracy that the world admires, that every citizen is equal under the law – even the prime minister – and no one, not even him, is above it.

It was a privilege to play a leading role in helping to safeguard our parliamentary sovereignty, and as such I am, on any view, a person with a genuine and substantial interest in the matter of defending MPs’ voices.

The letter I received demonstrates that Johnson has grudgingly accepted that proroguing parliament would be illegal. But it also provides the key to understanding why he has instead opted for dissolution. This is his last chance to make a no-deal Brexit happen.

What a travesty it is that the high priests of Leave in 2016, who insisted to all of us that Brexit would mean a return to parliamentary sovereignty, are undermining and circumventing parliamentary sovereignty in order to deliver their hard Brexit.

All now depends on that same parliamentary sovereignty: MPs of all parties must summon the courage to hold an overweening executive to account and do what is right in the name of the people they are elected to represent.

The next month will be critical in the life of our nation and will shape all our fortunes for decades to come. MPs will never be forgiven if they fail in their duty at this critical time.

• Gina Miller is a businesswoman and transparency activist