This article is more than 1 year old

This article is more than 1 year old

A no-deal Brexit could result in rising food and fuel prices, disruption to medicine supplies and public disorder on Britain’s streets, according to secret documents the government was forced by MPs to publish on Wednesday.

A five-page document spelling out the government’s “planning assumptions” under Operation Yellowhammer – the government’s no-deal plan – was disclosed in response to a “humble address” motion.

The content of the document was strikingly similar to the plan leaked to the Sunday Times in August, which the government dismissed at the time as out of date.

That document was described as a “base case”; but the new document claims to be a “worst-case scenario”.

Led by former attorney general Dominic Grieve, and passed by the House of Commons on Monday night as Boris Johnson prepared to suspend parliament, the motion demanded the publication of the documents, large sections of which had been leaked in August.

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At the time, Downing Street claimed the document had been superseded, and government sources suggested it had been leaked by disaffected former ministers. Former chancellor Philip Hammond later demanded an apology from Johnson, when it emerged the date on the document was August, after the PM took power.

The document, which says it outlines “reasonable worst case planning assumptions” for no deal Brexit, highlights the risk of border delays, given an estimate that up to 85% of lorries crossing the Channel might not be ready for a new French customs regime.

“The lack of trader readiness combined with limited space in French ports to hold ‘unready’ HGVs could reduce the flow rate to 40%-60% of current levels within one day as unready HGVs will fill the ports and block flow,” it warns.

This situation could last for up to three months, and disruption might last “significantly longer”, it adds, with lorries facing waits of between 1.5 days and 2.5 days to cross the border.

The reliance of medical supplies on cross-Channel routes “make them particularly vulnerable to severe extended delays”, the report says, with some medicines having such short shelf lives they cannot be stockpiled. A lack of veterinary medicines could increase the risk of disease outbreaks, it adds.

On food supplies, supplies of “certain types of fresh food” would be reduced, the document warns, as well as other items such as packaging.

It says: “In combination, these two factors will not cause an overall shortage of food in the UK but will reduce availability and choice of products and will increase price, which could impact vulnerable groups.”

Later, it adds: “Low income groups will be disproportionately affected by any price rises in food and fuel.”

On law and order it warns: “Protests and counter-protests will take place across the UK and may absorb significant amounts of police resource. There may also be a rise in public disorder and community tensions.”

The documents also outline a potential impact on cross-border financial services and law enforcement information sharing.

It says Gibraltar could face significant delays on its border with Spain, with four-hour waits likely “for at least a few months”.

The document also concedes that there will be a return to some sort of hard Irish border despite a UK insistence it will not impose checks: “This model is likely to prove unsustainable due to significant economic, legal and biosecurity risks and no effective unilateral mitigations to address this will be available.”

The expectation, it adds, is that some businesses will move to avoid tariffs, and others will face higher costs.

The government claimed on Wednesday night that the leaked document was “never a base or central case”.

“Some iterations of the Yellowhammer assumptions have used the phrase ‘base scenario’ to describe some baseline parameters – such as the UK will leave on a particular date and trade on WTO terms – upon which the worst case assumptions are then built. This has never meant that Yellowhammer is a base or central scenario and to suggest otherwise is a gross misrepresentation,” said a government source.

The government refused to comply with the second part of MPs’ request, which demanded the release of messages relating to the suspension of parliament sent by Johnson’s senior adviser, Dominic Cummings and various other aides on WhatsApp, Facebook, other social media and both their personal and professional phones.

In a letter to Grieve, Michael Gove, the chancellor of the Duchy of Lancaster, said the request was “inappropriate in principle and in practice, would on its own terms purport to require the government to contravene the law, and is singularly unfair to the named individuals”.

Grieve told MPs on Monday he had information from public officials that the correspondence contained a “scandal”.

The House of Commons voted, by 311 to 302, for the government to publish the information, giving the prime minister a deadline of 11pm on Wednesday to comply.

Following publication of the document, Grieve said: “As a One Nation Conservative I am deeply fearful of the long-term damage a reckless approach – which knowingly risks prosperity, increases poverty and even threatens medical supplies – will do to both the people and our party. This must be stopped.”

Gove has been given the task of ramping up no-deal preparations across government. The chancellor, Sajid Javid, set aside an extra £2bn at last week’s spending review for the task, taking the total now allocated to no-deal planning to £8bn.

Johnson has lost every vote in parliament since he became prime minister in July, including on his two attempts to trigger a snap general election for next month.

The prime minister sparked a fierce backlash inside the Tory party last week by removing the whip from 21 rebels who supported backbench-led legislation to force him to request a Brexit delay if he fails to pass a new deal through parliament by mid-October.

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Those expelled include former justice secretary David Gauke, Hammond, and Winston Churchill’s grandson, Nicholas Soames.

Chief whip Mark Spencer has now written to some of them, confirming that they are entitled to appeal the decision – and hinting that future loyalty to the government could boost their cause.

One of the 21 MPs said: “It was one of the most self-unaware letters I’ve received in some time. From people who are serially disloyal and decimated their own minority government. I don’t want it back ...

“All it did in my local community was confirm that the Conservative party is now led by a narrow sect who wouldn’t be out of place in the Muppet version of the Handmaiden’s tale. It’s like being asked by its captain if you want to get back on the Titanic.”

Senior Conservatives expect the whips to be less accommodating to those MPs who have been fiercely critical of the government’s stance.

Sam Gyimah has received a letter but is not intending to seek to have the whip restored, the Guardian understands; while Hammond is hoping to challenge the original suspension in a bid to have it overturned.