There has been a lot of talk about 'Operation Yellowhammer'. In January of this year, little was known about it. pjc50 wrote in an answer dated January 2019:

(Personally I think it's more likely that some kind of emergency will be declared at the point of Brexit resulting in the election being delayed, under the Civil Contingencies Act. A telephoto shot of a document headed "Operation Yellowhammer" supports this theory, but there are no details.)

In September of 2019 (over 9 months after the public had been aware of the term, given the quote above), Parliament voted for the release of the Yellowhammer documents. From the Guardian:

Dominic Grieve is now making his application for a standing order 24 debate. Here is the motion he is proposing.

Dominic Grieve is opening the debate on his standing order 24 motion that would force the publication of the government’s Operation Yellowhammer document and No 10’s private prorogation correspondence.

The motion they speak of has passed and the UK government has released a scanned document on titled 'Operation Yellowhammer'. It seems to be a mere 5-page summary with little text and small bulletpoints.

A senior journalist for the Sunday Times, Rosamund Urwin, tweeted:

What's different about the new Yellowhammer document that the government has just published compared with the one I got hold of last month? The heading. What did the version I had say? BASE SCENARIO Now what does the new one say? HMG Reasonable Worst Case Planning Assumptions

With that in mind, I'm wondering if there's any indication (in addition to the tweet above) if these are not the actual Yellowhammer documents or not the complete Yellowhammer documents. Is there any such indication or was the government only required to publish a summary and is the now released document that summary?

1 Answer 1


The Humble Address said, "... that Ministers be further directed 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."

The single document provided does not seem to meet the requirement of the Humble Address for "all the documents". Michael Gove, Chancellor of the Duchy of Lancaster, wrote in a letter to Dominic Grieve:

The Government is, of course, committed to sharing information with Parliament. When doing so however, the Government must comply with its legal obligations and be mindful of its duty to balance a commitment to transparency with the broader public interest. The importance of ensuring both a safe space for policy development, and the provision of confidential advice to Government from officials has long been recognised in government practice, in the Ministerial Code, and by Parliament itself, including in the Freedom of Information Act 2000. As you will also be aware, by longstanding convention under successive Administrations of all political colours, the Government does not release Cabinet and Cabinet Sub-Committee papers. This is stated within the Ministerial Code and is reflected in the Cabinet Manual.

One can infer from the rest of the letter that there may be other documents pertaining to Operation Yellowhammer that will not, for the time being, be provided.

The document doesn't explicitly profess to be a summary or a detailed plan. It is headed, "Reasonable worst case planning assumptions". Michael Gove wrote to Hillary Benn that it is

neither an impact assessment, nor a prediction of what is most likely to happen. It describes what could occur in a reasonable worst case scenario, thus providing a deliberately stretching context for government planning to ensure that we are prepared for Exit.

  • This answer would be improved by laying bare the problems with those government statements. Also, I'm not entirely sure it answers JJJ's question. Commented Sep 12, 2019 at 9:12

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