In the United Kingdom, the term "List X" designates companies and specific sites within those companies that have been approved to handle classified government information. This information is marked as "Secret" or above, or if from international partners, it's marked "Confidential" or above.

Security and Access

List X status is equivalent to holding a Facility Security Clearance (FSC) in other countries. Companies on this list are often involved in vital defense research or manufacturing projects crucial to national security. The designation is administered by the Defence Security and Assurance Services (DSAS), part of the UK's Ministry of Defence.

Classified Information

It's crucial to note that the full list of List X companies is itself classified information. The general public cannot access this list for security reasons.

Why List X Matters

• Government Contracts: List X companies are eligible to bid on and handle sensitive government contracts with classified information requirements.
• National Security: Companies with this designation play a significant role in protecting the UK's national security interests, particularly in the defense sector.
• Rigorous Standards: List X companies must meet strict security protocols and procedures to protect classified information.

Finding Information (with limitations)

While the full List X remains confidential, there are some avenues to learn more, with the understanding that specific companies will not be revealed:

• Government Resources: The Government website (https://www.gov.uk/) may provide general information on List X procedures and requirements.
• Defense Industry Publications: Trade publications focused on the defense sector may offer insights on the types of companies that would typically qualify for List X status, without listing specific names.
• Freedom of Information Act (FOIA) Requests: While unlikely to be successful in acquiring the full List X, FOIA requests might yield some related, declassified information. (https://www.whatdotheyknow.com/)

References

• GOV.UK - Security Requirements for List X Contractors: (https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/62334/Security-Requirements-for-List-X-Contractors-PUBLIC-v7-Oct2011.pdf)
• Wikipedia - List X site: (https://en.wikipedia.org/wiki/List_X_site)

Important Note: It is crucial to respect the confidential nature of the List X designation. Attempting to discover specific company names through illicit means could have serious legal consequences.