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Operation Yellowhammer is the codename used by the UK Treasury for cross-government civil contingency planning for the possibility of a no-deal Brexit.[1][2][3] In the event of exit with no-deal, the UK's unilateral departure from the EU could disrupt, for an unknown duration, many aspects of the relationship between the UK and European Union, including financial transfers, movement of people, trade, customs and other regulations.[4] Operation Yellowhammer is intended to mitigate, within the UK, the effects of this disruption,[2] and would be expected to run for approximately three months.[5] It has been developed by the Civil Contingencies Secretariat (CCS), a department of the Cabinet Office responsible for emergency planning.

In early August 2019, after Boris Johnson had become Prime Minister, the Cabinet Office "was not able to confirm" that the Operation Yellowhammer plan remained in place,[6] although a Yellowhammer document from earlier that month was leaked in mid-August and continues to be updated.[7]

On 3 September 2019, Chancellor of the Duchy of Lancaster Michael Gove, whose responsibilities include preparations for a no-deal Brexit, said in the House of Commons: "Operation Yellowhammer assumptions are not a prediction of what is likely to happen, they are not a best-case scenario or a list of probable outcomes, they are projections of what may happen in a worst-case scenario."[8] An otherwise unchanged version of Yellowhammer leaked earlier to The Times was titled "base case" scenario rather than the "reasonable worst case" scenario of the officially published document; a copy given to the Scottish government was titled "base scenario".[9][10]

The Sunday Times has reported that Yellowhammer is one of three scenarios being studied, with the other two being Kingfisher, involving a support package for distressed British businesses, and Black Swan, a disaster scenario.[11] Michael Gove has characterised the report as inaccurate.[12]

Disclosure and namingEdit

The existence of the operation leaked on 6 September 2018, when a press photographer captured a snapshot of a document revealing some "no-deal" plans and the HM Treasury codename for them.[13] The document appeared to indicate the CCS had been used in anticipation of government policy.[14] No further details were revealed. The National Audit Office subsequently made public some documents about the operation.[15]

The operation code name "Yellowhammer", which relates to a small songbird, was chosen at random according to The Times.[16]

On 2 February 2019, The Times received leaked documents with this code name, about Department for Transport command and control structure plans.[17][2]


Operation Yellowhammer covers actions to be taken in a no-deal scenario,[1] some of which would be implemented prior to the date of leaving.[2]

On 29 January 2019 the House of Commons voted, in a non-binding ballot, to reject a no-deal Brexit.[18] unless the House of Commons were to accept the Brexit withdrawal agreement, or the EU's other members were to grant the UK an extension under Article 50 of the Lisbon Treaty, or the UK were to revoke its Article 50 notice, the United Kingdom would by default have exited the EU on 29 March 2019 with no deal.[19]

On 20 March 2019, Kent County Council activated plans to keep roads, hospitals and schools open, and the Brexit secretary, Steve Barclay, said that Operation Yellowhammer command and control structures would be "enacted fully" on 25 March 2019 unless a new exit date was agreed between the UK and the EU.[2][20] On 21 March 2019, the Ministry of Defence staffed a bunker under its Whitehall headquarters to coordinate no-deal related military activities under Operation Redfold,[5] and the COBRA emergency committee took control of no-deal planning with intentions to implement national contingency plans on 25 March 2019.[21][22][Note 1]

Late on 21 March 2019, possible new exit dates were agreed between the UK and the EU:

  • 22 May 2019 if the House of Commons approved the Brexit withdrawal agreement by 29 March 2019;[Note 2] or
  • 12 April 2019 otherwise.[23][24]

Consequently, full activation of Operation Yellowhammer was postponed until 8 April 2019.[25][26]

On 10 April 2019 the European Council granted the UK a six-month extension; Yellowhammer's 6,000-strong civil service team was disbanded a few weeks afterwards, with most members returning to their usual activities. Developments since then – with Theresa May resigning as leader of the Conservative Party and both candidates to replace her talking of leaving without a deal by the 31 October deadline – may make it necessary to resume preparations.[27] The Institute for Government said that the government may never be as ready for a no-deal Brexit as it was for the original departure date at the end of March. According to Joe Owen, the IfG's Brexit programme director, reinstating Yellowhammer and reinstating thousands of civil servants to implement no-deal contingency plans is a formidable task; everything will need to be "resurrected and restaffed, and earlier rounds of staff training will need to be repeated".[28] According to the Financial Times and others, this is a sign that we have already run out of time.[27]

EU preparednessEdit

The European Union issued a press release on 25 March 2019 indicating it had completed preparations for an increasingly likely "no-deal" scenario on 12 April 2019.[29]


Operation Yellowhammer was developed by the Civil Contingencies Secretariat, though COBRA took control on 25 March 2019.[21] It will be organised via a Command and control structure (C3),[21] which will co-ordinate:[21]

  • Up to 30 UK Government departments
  • If a Government department's contingency plans are inadequate Operation Yellowhammer will take over planning and decisions for that department.
  • Approximately 40 local resilience forums in England and Wales[21][5]
  • Similar bodies in Northern Ireland and Scotland
  • Governing authorities for the United Kingdom, overseas territories and crown dependencies
  • Co-ordination with impacted industries and sectors.

Major decisions will be taken by the European Union Exit and Trade (Preparedness) Sub-Committee, set up in January 2019[30] and chaired by the prime minister. It will have wide-ranging powers to order emergency measures, including use of the military, and overriding regulations.[5]


The CCS may work with the Department for Exiting the European Union (DExEU) to achieve an objective for Brexit work, with the DExEU concentrating on new policies, legislative changes and required funding changes with the CCS dealing with steps to mitigate and manage short-term disruption. An example objective would be Continuity of supply of medicines into the UK after no deal exit from the EU falling within the areas of risk of key goods crossing borders and transport systems. Arrangements for prioritisation of key goods, additional ferry capacity and having procedures in place for operation customs operations that are effective immediately from the Brexit date are some of the areas covered.[15]:15

Areas of riskEdit

Operation Yellowhammer identifies 12 areas of risk. These include the food and medicine supply chains and the status of UK citizens residing in the EU.[2] There are also three risks common to all areas.[15]:7 The twelve areas of risk identified are: transport systems, people crossing borders, key goods crossing borders, healthcare services, UK energy and other critical systems, UK food and water supplies, UK nationals in the EU, law enforcement implications, banking and finance industry services, Brexit and the Irish border, specific risks to overseas territories and Crown dependencies (including the effect of Brexit on Gibraltar) and national security.[15]:7 Risks common to all areas identified are: legal, communications and data.[15]:7

Costs and resourcesEdit

In March 2019 the CCS had 56 people working internally on the programme; it is estimated 140 would be needed to maintain the operations centre and it has been budgeted to cost £1.1 million in 2018–2019. This is in the context of the UK Treasury allocating £1.5 billion for Brexit preparations by government departments in 2018–2019.[21]

3,500 troops were placed on standby to 'assist the civil power' in the event of issues arising from a no-deal exit, although the Ministry of Defence had only disclosed their mission will be to "support government planning".[5][31]


On 21 March 2019, the UK government's decision to risk a no-deal Brexit and to invoke Operation Yellowhammer was criticised by the First Minister of Scotland, Nicola Sturgeon.[32] Her sentiments were echoed by the First Minister of Wales, Mark Drakeford.[33] On 22 March confidential Cabinet documents on Operation Yellowhammer were obtained by The Guardian newspaper. The document warned that ministers could need to work 22.5-hour days,[34] and departments would have to work 24 hours a day for at least twelve weeks without input from higher up in government. A source with knowledge of the operation said that, although planning had stepped up, the overall picture remained chaotic and "rudderless".[5]

August 2019 leakEdit

In mid-August 2019 an official cabinet Yellowhammer document[35] from earlier that month was leaked. the paper gave base-case planning assumptions in the event of a no-deal Brexit which could lead to food, medicine and petrol shortages, with a hard border in the island of Ireland, and a "three-month meltdown" at ports unable to cope with extra checks. There could be protests requiring police action, and thousands of jobs could be lost as two oil refineries closed. Government ministers disputed the report and dismissed its warnings as "worst-case".[36][37] The Sunday Times, according to The Observer, said that a senior Whitehall source said "This is not Project Fear, this is the most realistic assessment of what the public face with no deal. These are likely, basic, reasonable scenarios – not the worst case."[38]

September 2019 publicationEdit

A humble address was passed by the House of Commons on 9 September 2019 requiring the government to "to lay before this House no later than 11.00pm Wednesday 11 September all the documents prepared within Her Majesty's Government since 23 July 2019 relating to operation Yellowhammer and submitted to the Cabinet or a Cabinet Committee".[39][40]

In compliance, on 11 September the Government released a five-page document entitled "Operation Yellowhammer: HMG Reasonable Worst Case Planning Assumptions as of 2 August 2019".[41][42] Other than a change of title – from "Base Scenario" to "Reasonable Worst Case Planning Assumptions" – and one redacted paragraph reportedly dealing with the impact on the oil refining industry,[43] the document was essentially identical to the one leaked in August.

See alsoEdit

Notes and referencesEdit


  1. ^ This announcement was made prior to the agreement between the UK and the EU27 late on 21 March 2019, for an extension to October 31.
  2. ^ According to the European Union (Withdrawal) Act 2018 (before subsequent amendments), should the House of Commons not approve the withdrawal agreement by 29 March 2019, the default legal position would be that the UK would have exited the EU on 12 April 2019.


  1. ^ a b "Operation Yellowhammer: Photo of secret government no-deal Brexit papers reveals questions over 'rail access to the EU". The Independent. 6 September 2018. Archived from the original on 6 September 2018. Retrieved 6 September 2018.
  2. ^ a b c d e f correspondent, Lisa O'Carroll Brexit (20 March 2019). "UK's emergency plans for no-deal Brexit begin to be put into action". The Guardian. ISSN 0261-3077. Archived from the original on 20 March 2019. Retrieved 20 March 2019.
  3. ^ "MoD hosts no-deal planning in bunker". BBC News. 21 March 2019. Retrieved 22 March 2019.
  4. ^ Morris, Chris (14 October 2017). "Brexit: What would 'no deal' look like?". BBC. Archived from the original on 24 October 2018. Retrieved 6 September 2018.
  5. ^ a b c d e f Nick Hopkins (22 March 2019). "Secret Cabinet Office document reveals chaotic planning for no-deal Brexit". The Guardian. Archived from the original on 23 March 2019.
  6. ^ Schraer, Rachel; Edgington, Tom (6 August 2019). "No-deal Brexit: What is the UK government doing to prepare?". BBC. Archived from the original on 11 August 2019. Retrieved 15 August 2019.
  7. ^ Ailbhe Rea (19 August 2019). "The government just emailed confidential Brexit information to the wrong person". New Statesman. Retrieved 20 August 2019.
  8. ^ "Emergency debate to block no deal rages in the Commons after Johnson loses majority". ITV News. 3 September 2019. Retrieved 4 September 2019.
  9. ^ Stewart, Heather (12 September 2019). "Brexit: no-deal chaos fears as ministers forced to publish secret papers". The Guardian. Retrieved 12 September 2019.
  10. ^ "First Minister's Questions LIVE: Nicola Sturgeon faces questions over Edinburgh Sick Kids and Yellowhammer".
  11. ^ Wheeler, Caroline; Urwin, Rosamund (18 August 2019). "'This is not Project Fear — it's what we face after no-deal Brexit'". The Sunday Times. ISSN 0956-1382. Retrieved 11 September 2019.
  12. ^ Doherty, Jennifer (18 August 2019). "Brexit Could Plunge U.K. Into Economic Chaos: Leaked 'Operation Yellowhammer' Government Documents Reveal 'Worst Case Scenario'". Newsweek. Retrieved 12 September 2019.
  13. ^ Kuenssberg, Laura (6 September 2018). "Snatched pic gives insight into 'no deal' Brexit planning". Archived from the original on 6 September 2018. Retrieved 6 September 2018.
  14. ^ Islam, Faisal. "It's been another first for Brexit". Sky. Archived from the original on 6 September 2018. Retrieved 7 September 2018.
  15. ^ a b c d e National Audit Office - Cabinet Office Civil Contingencies Secretariat (12 March 2019). "Contingency preparations for exiting the EU with no deal" (PDF).
  16. ^ Wright, Oliver (7 September 2018). "Prepare for cuts under no-deal Brexit, Treasury tells Whitehall in Operation Yellowhammer". The Times. Retrieved 22 March 2019.
  17. ^ @SamCoatesTimes (2 February 2019). "37 page "Operation Yellowhammer" no deal planning pack for staff leaks. Marked "official sensitive"" (Tweet). Retrieved 2 February 2019 – via Twitter.
  18. ^ "Brexit: How did my MP vote on the amendments?". BBC. 29 January 2019. MPs vote to reject leaving without a deal. Archived from the original on 6 February 2019. Retrieved 20 March 2019.
  19. ^ Morris, Chris (20 March 2019). "Brexit delay: How can Article 50 be extended?". BBC. Archived from the original on 2 February 2019. Retrieved 21 March 2019.
  20. ^ Zeffman, Henry; Wright, Oliver (21 March 2019). "Brexit vote: Cobra takes over planning for no-deal". The Times. Retrieved 21 March 2019.
  21. ^ a b c d e f Guyoncourt, Sally (21 March 2019). "Operation Yellowhammer: what are the Government's emergency plans for a no-deal Brexit and how would they work?". Archived from the original on 22 March 2019.
  22. ^ "Brexit: Govt preparing to enter 'very high readiness mode' for no deal". Sky News. Retrieved 22 March 2019.
  23. ^ "EU leaders agree Brexit delay plan". BBC News. 22 March 2019. Retrieved 22 March 2019.
  24. ^ Adler, Katya (22 March 2019). "Brexit pushed back by at least two weeks". BBC News. Retrieved 22 March 2019.
  25. ^ Zeffman, Henry (23 March 2019). "No-deal emergency plan is put on ice after Brexit delay". The Times. Retrieved 29 March 2019.  
  26. ^ "Operation Yellowhammer: departments told not to overload central command - Civil Service World".
  27. ^ a b Anonymous civil servant (28 June 2019). "I'm a civil servant – and we can't make Boris Johnson's no-deal fantasy into reality". The Guardian.
  28. ^ Richard Johnstone (5 June 2019). "Brexit: Whitehall churn means government may never be as ready again for no deal, says IfG". Civil Service World.
  29. ^ "Daily News – 25.03.2019". European commission Press Release Database. Archived from the original on 25 March 2019.
  30. ^ David Lidington (8 January 2019). "Cabinet Committees and Implementation Task Forces:Written statement - HCWS1238". UK Parliament. Retrieved 22 March 2019.
  31. ^ Edgington, Tom; Schraer, Rachel (23 March 2019). "No-deal Brexit: What is the UK government doing to prepare?". BBC. Archived from the original on 23 March 2019.
  32. ^ "Meeting of the Parliament 21 March 2019 [Draft]".
  33. ^ Melanie May (22 March 2019). "First Minister tells charities to put aside normal activities and plan for No Deal". Retrieved 22 March 2019.
  34. ^ "'Leaked' plans for no-deal Brexit reveal how chaotic it could really be". 22 March 2019.
  35. ^ "Leaked Yellowhammer cabinet document". August 2019. Retrieved 18 August 2019.
  36. ^ Rowena Mason (18 August 2019). "No 10 furious at leak of paper predicting shortages after no-deal Brexit". The Observer.
  37. ^ Urwin, Rosamund; Wheeler, Caroline (18 August 2019). "Operation Chaos: Whitehall's secret no‑deal Brexit preparations leaked". The Times. Retrieved 19 August 2019.
  38. ^ Rowena Mason (18 August 2019). "Brexit: leaked papers predict food shortages and port delays". The Observer.
  39. ^ "MPs order Johnson to hand over aides' messages about prorogation". The Guardian. 9 September 2019. Retrieved 9 September 2019.
  40. ^ "Prorogation (Disclosure of Communications) 09 September 2019". House of Commons Hansard. Retrieved 9 September 2019.
  41. ^ "Brexit: Operation Yellowhammer no-deal document published". BBC News. 11 September 2019. Retrieved 11 September 2019.
  42. ^ Latest Yellowhammer Planning Assumptions
  43. ^ "Official no-deal document confirms government planning for delays, disruption and disorder". The Independent. 11 September 2019. Retrieved 11 September 2019.

External linksEdit