FCO 141 – insecticide testing and public health impact

FOI request reference: CAS-89442
Publication date: August 2022


The TNA online catalogue on 7 July 2022 says about documents in the record series FCO 141:

This series has been temporarily withdrawn from public access due to evidence of historical preservation treatment of these files indicating insecticide use. Having tested a sample of the files in the series, all show traces of historic insecticides. The National Archives is working with specialist consultants to establish a risk assessment and safe handling guidance in order to create avenues for access to this series. https://discovery.nationalarchives.gov.uk/details/r/C12269323

Under the Freedom of Information Act 2000 I am requesting copies of all documents held by the National Archives

• providing background to the decision to test a sample of FCO 141 files
• the results of those tests
• any assessments (whether formal or informal) made to date of the risks to the documents or to people coming into contact with the documents of the traces of historic insecticide that have been found.


Information withheld.


I can confirm that The National Archives holds information relevant to your request. However, we are unable to provide you with the information you have requested because it is covered by the exemption at section 36(2)(b)(c) and 40(2) of the FOI Act, which exempts information if it would prejudice the conduct of public affairs. For further information about why these exemptions have been applied, please see the explanatory annex at the end of this letter.

Please see the following web link to our latest public update (2nd August 2022) on the withdrawal of the FCO 141 series.

Explanatory annexe

Exemptions applied:

Section 36: Prejudice to Effective Conduct of Public Affairs

Section 36 (2) (b-c) exempts information from release if, in the reasonable opinion of a qualified person, disclosure of the information would, or would be likely to; (b)(i) inhibit the free and frank provision of advice, (b)(ii) the free and frank exchange of views for the purposes of deliberation, or would otherwise prejudice, or would be likely to otherwise prejudice, (c) the effective conduct of public affairs.

Section 36 is a qualified exemption and we are required to conduct a public interest test when applying any qualified exemption. This means that after it has been decided that the exemption is engaged, the public interest in releasing the information must be considered. If the public interest in disclosing the information outweighs the public interest in withholding it then the exemption does not apply and the information must be released. In the FOI Act there is a presumption that information should be released unless there are compelling reasons to withhold it.

With the agreement of the Qualified Person, who in this case is the Chief Executive and Keeper of The National Archives, in whose reasonable opinion this exemption is engaged, the public interest has now been concluded and the balance of the public interest has been found to fall in favour of non-disclosure.

Considerations in favour of the release of the information included the principle that there is a public interest in showing a true and open account of information that influences government decision-making, making for greater accountability and increasing public confidence in the integrity of the decisions made. There is a general public interest in transparency concerning information which is relevance to issues of public health and safety, as well as access to historic records.

However, it is also considered that the release of the information requested would prejudice and/or otherwise inhibit both the free and frank exchange of views for the purposes of deliberation, and the effective conduct of public affairs.

At the time this FOI request was received a complete list of affected records in the FCO 141 series had not been compiled, and records with warning labels were still being discovered. Similarly, at the time that this FOI request was received the full range of tests on affected records had not been completed, and the results of some preliminary tests were still awaiting confirmation. The withdrawal of the FCO 141 series remains a live issue for The National Archives. Relevant forensic data is still being gathered, and the implications arising from this data concerning the extent of affected records, and test results on these records, requires a safe space for discussion.

It is important that officials are able to exchange views freely and frankly and to fully discuss the implications and issues arising from the relevant data. To prematurely release incomplete data concerning our testing of the records and the extent of any potential contamination and would likely act as an inhibitor to necessary discussions. This would not be in the public interest and would be likely to prejudice The National Archives’ ability to carry out its statutory obligations, to communicate effectively with the public, and to consult on this issue with other government departments. As such, release of this information is seen to be likely to both inhibit a safe space and create a chilling effect for the free and frank exchange of ideas, thereby prejudicing the effective conduct of public affairs.

After careful consideration, it has been decided that the balance of the public interest lies in favour of withholding the information on this occasion and that the factors for non-disclosure outweigh any benefits of release.

Further guidance on the application of this exemption can be found at:

Section 40(2): Personal Information where the applicant is not the data subject

Section 40 exempts personal information about a ‘third party’ (someone other than the requester), if revealing it would breach the terms of Data Protection Legislation. Data Protection Legislation prevents personal information from release if it would be unfair or at odds with the reason why it was collected, or where the subject had officially served notice that releasing it would cause them damage or distress. Personal information must be processed lawfully, fairly and in a transparent manner as set out by Art. 5 of the United Kingdom General Data Protection Regulation (UK GDPR).

In this case the exemption applies because the requested material contains information which would identify junior members of staff.

Publishing the names and contact details of junior members of staff is considered an unfair use of personal data. Junior members of staff would have no expectation that information about their positions would be made available in the public domain; to do so would be unfair and contravene the first data protection principle of the Data Protection Act. As such, the names, positions and contact details of junior officials are withheld under section 40 (2) of the FOI Act.

Further guidance about the publication of junior staff names can be found here: