Working to make government more effective


Operation Yellowhammer


This explainer was written for preparations for the possibility of a no-deal Brexit in October 2019.

​What is Operation Yellowhammer?

Operation Yellowhammer is the government’s contingency planning for its response to the most severe anticipated short-term disruption under a no-deal Brexit – known as its ‘reasonable worst case’ scenario. It covers 12 key areas of risk, including food and water supplies, healthcare services, trade in goods and transport systems. Government departments are setting up 24-hour operational centres to co-ordinate responses to issues as they arise.

Operation Yellowhammer is a key part of the government’s no-deal preparations.

As part of this scenario, the government assumes that there will be no deals in place with the EU or member states to manage the impact, that business will remain very unprepared, and that the Brexit extension from March to October will mean that businesses are in some cases less prepared – due to ‘Brexit fatigue’ and the seasonal impacts.

What is the government’s Yellowhammer scenario and what has it done to mitigate the possible impacts?


Yellowhammer scenario

Government mitigations include

Trade in goods

EU member states will apply EU mandatory controls on day one after a no-deal Brexit. For the Dover–Eurotunnel crossing, the UK’s key trade artery with the EU, this will mean:

  • 50–85% of lorries may not be ready for new controls, e.g. customs.
  • Flow of trade reduced by 40–60% of current levels. Annually, around 4.2 million lorries pass through Dover and the Eurotunnel. This reduction in trade would be the equivalent of between 0.85 and 1.25 million lorries being able to pass in the six-month period after no deal.
  • Disruption continues for three months, before flow returns to 30–50% lower than current standards (equivalent of between 2.1 and 2.9 million lorries over the course of a year).
  • Significant queues in Kent with maximum delays of 1.5–2.5 days.
  • Disruption will mean some EU logistic firms stop operating in the UK.

The UK government’s key focus is to improve trader readiness to help flow through Calais, with the new communications campaign aimed at building awareness.

The government also aims to try and prevent lorries from entering Kent and reaching Dover unless they have the necessary paperwork for smooth passage in France – using roving controls and ‘pop-up’ checking sites.

Preparedness in France is a major factor, but there have been recent improvements, including improved capacity in Calais.
UK citizens travelling to the EU

Increased immigration checks could lead to passenger delays for those using Eurostar, the Channel tunnel or ferries in Dover – i.e. where French checks take place in the UK.

Some delays are likely for UK citizens arriving at EU airports and ports.

No UK government unilateral mitigations.

The UK is reliant on EU member states preparations and approach to checks.
Energy and electricity

No disruption to electricity or gas interconnectors on day one.

Within months or years, the UK could face significant price increases for households and businesses.
The government's mitigations are not clear.

Unless trade through Dover–Eurotunnel is mitigated, the supply of medicines and medical supplies could be impacted. 75% of medicines come into the UK through that route.

Existing supply chains – affected by trade patterns and regulation – make medicines particularly vulnerable to delays.

Only some medicines can be stockpiled, and stockpiles will not be able to last the full six months of expected delays.

The government is buying planes and ships to ensure medicines can come in to the UK even if commercial trade routes are blocked or face major delays.

The government is exploring whether pharmacists have the ability to offer patients different medicines to those on prescription, and see if they serve the same purpose and can help manage supply.

Veterinary medicines

Any reduction, delay or stop in supply of medicines for veterinary use would reduce the UK’s ability to prevent and control disease outbreaks – which could impact animal welfare, the environment, food safety/availability and zoos.

Industry stockpiling for October is not able to match the stockpiling done in March.
As above, but the government is concerned it would not be a financially viable mitigation to fully manage the risk.

Certain types of fresh food will decrease. Critical dependencies for the food chain may be in shorter supply.

No overall shortage of food but a reduction in availability/choice and an increase in prices, which could affect the most vulnerable groups.

Problems exacerbated by the run up to Christmas and the fact that it isn’t growing season in the UK.

The UK government is not able to fully anticipate all potential impacts.

The UK government is concerned about panic buying.

Mitigations include encouraging businesses to stockpile.

But mitigation for food is heavily dependent on issues around Dover/Calais. Food is not seen as a ‘category one’ item so, unlike medicines, will not be transported using ships or planes procured by the government.

Some cross-border financial services will be disrupted.

Flow of personal data will be disrupted if an alternative legal basis is not in place. A data adequacy decision (allowing freer transfer of personal data) could take years.
Government communications campaign to improve business readiness.
Law enforcement Law enforcement data and information sharing between UK and EU will be disrupted. The UK government is starting to use other – less effective – routes to share information with member states’ law enforcement authorities.
UK citizens in the EU

UK nationals will lose their EU citizenship and associated rights and access to services.

There are gaps in the understanding of different member states’ proposals for UK citizens rights. Depending on the member state involved, this could result in gaps in healthcare cover – possibly resulting in payment.
The UK government is engaging with member states to try and secure similar rights to those offered by the UK government to EU citizens.

Disruption in the supply of goods (including food), medicines, waste removal and possible delays of four hours or more for workers, residents and tourists moving across the border.

Prolonged delays are likely to impact Gibraltar’s economy in relation to services and data flows.
Decisions to invest in contingency infrastructure have still not been taken and there are concerns that the necessary legislation will not be passed in time.
Protests Protests and counter-protests will take place across the UK and may absorb significant amounts of police resource. There may be a rise in public disorder and community tension. The government's mitigations are not clear.
Traffic and fuel

Regional traffic disruption caused by border delays (for example, in Kent) could affect fuel distribution within the local area.

Customer behaviour could lead to local shortages in other parts of the country.
The government's mitigations are not clear.
Impact on consumers Low-income groups will be disproportionately affected by any price rises in food and fuel. The government's mitigations are not clear, but Project Kingfisher is another government no-deal project that could seek to mitigate some of the consequences.
Northern Ireland

The UK government will operationalise a “no checks with limited exceptions” model to avoid an immediate risk of a return to a hard border on the UK side.

Expect some businesses will stop trading, or relocate, to avoid paying the EU tariff. Others will continue to trade with higher costs which may be passed on to consumers. The agri-food sector will be hardest hit.

Disruption to key sectors and job losses are likely to result in protests and direct action, as well as a growth in illegal trade particularly in the border communities.

The government acknowledges the “no checks” model will be unsustainable as there are no effective unilateral mitigation measure to address economic, legal and biosecurity risks.

The government will need to introduce direct rule in Northern Ireland to manage this situation – but the prorogation of Parliament leaves little time to do this before the 31 October Brexit deadline.

The government recognises there will be significant pressure to reach a deal with the EU within days or weeks of a no-deal Brexit.


Up to 282 EU and European Economic Area fishing vessels could illegally enter UK waters on day one.

The UK government and devolved maritime agencies’ enforcement and response capabilities could be under pressure from competing demands.
The government is aiming for a sevenfold increase in the coverage of patrol vessels and introducing a significant increase in aerial surveillance to assist it in enforcement of new rules coming into effect after 1 November.
Adult social care

There is an assumption there will be no major change in adult social care.

However, an increase in inflation would significantly impact adult social care providers due to increasing costs. Smaller providers would be impacted within two to three months and larger providers within four to six months.
The government's mitigations are not clear.

Related content