List X Explained

List X








If you are a commercial company seeking to hold government information with a security classification of SECRET or above on your own premises you’ll need ‘List X’ accreditation. This article will give you a very brief introduction to List X, with useful links and points of contact that will help you in the process.

Originally published in 2013, this article was updated in May 2016 to reflect the new Government Security Classifications and the change of name for the MoD Accreditation Authority.

Update July 2017: If you are looking for List X guidance you will also find our latest articleHow to prepare your company for achieving List X of help.

What is List X?

The term ‘List X’ is the UK equivalent to Facility Security Clearance (FSC) used in the rest of the world. The term refers to contractors or subcontractors that have been placed on the List X database because they are carrying out work on their own premises that bears a UK Government classification of SECRET or above.

Sponsorship for List X

Companies cannot ‘apply’ for List X status; they must be ‘sponsored’ by a Contracting Authority (CA) that intends passing them classified information. The CA can be:

  • A UK government body;
  • An existing List X company;
  • Overseas government or defence contractors;
  • NATO

The CA will detail the security aspects of the List X requirement e.g. what classified information is to be held and why.

Who Manages List X?

As the Ministry of Defence (MoD) is the CA for the majority (85%) of List X sites, the whole process is managed by the MoD Defence Equipment & Support (DE&S) Principal Security Advisor (PSyA) based at Abbey Wood, Bristol. The PSyA maintains the database of approved List X sites and also a restricted access website for List X companies. For details of how to get access, phone the PSyA on 0306 79 34378.

List X Security Requirements

The process of obtaining List X is not just about an assessment of the physical controls in place at the premises where the classified information is to be held. It encompasses the whole security culture of an organisation including risk management, personnel security and security roles and responsibilities. For example, it is mandated that List X companies have a Board Level representative that accepts responsibility for maintaining the requirements of List X and informing the CA if any changes in the company are likely to impact on their List X status such as change in company ownership.

It is worth noting that the List X assessment does not cover the accreditation of IT systems. Accreditation of IT systems should be initiated with the CA’s accreditation authority ( Defence Assurance & Information Securityfor MoD ).

The Security Controller

Another mandated role for List X companies is the Security Controller. Specific duties include:

* Interpreting, implementing and monitoring compliance with List X security controls;
* Maintaining a relationship with the CA and/or MoD PSyA;
* Preparing and implementing company security instructions, Risk Management and Accreditation Document Sets (RMADS) and Security Operating Procedures (SyOPs);
* Education and awareness training;
* Incident management;
* Inform CA and MoD PSyA on changes to the List X requirement;
* Controlling visitors within the ‘need-to-know’ rule.

The Defence Industry Security Association (DISA) provide a variety of courses relevant to those working in the List X/Defence arena. Full details of these courses and of how to join DISA are shown on their website .

The Security Advisor & List X Assessment

The CA or MoD PSyA will appoint a Security Advisor who will be responsible for advising on the List X security requirements and inspecting the premises on an annual basis to ensure compliance. A List X Assessment, Checklist and Guidelines document is usually sent to the List X company at the start of the process and then annually. This document is in the form of a comprehensive questionnaire that captures the information necessary for approval for sites to handle, store, process or manufacture classified assets. It covers the Mandated Requirements (MR) listed in the Security Policy Framework and at the last count was nearly 50 pages long and takes considerable effort to complete.

Getting Help

The process of getting and maintaining List X can be a very time consuming and in some cases very expensive depending on the assets needing protection. Ascentor has a great deal of experience helping companies prepare for List X and managing the process.

The latest Ascentor List X article

This original article was originally published in April 2013. If you are looking for List X guidance you will also find our latest List X article ‘ How to prepare your company for achieving List X ‘ of help, published in June 2017.

For further information

If you have found this article of interest, the Ascentor blog regularly carries articles about cyber security and information assurance issues. You might also like to keep in touch with Ascentor by receiving our quarterly newsletter and following us on LinkedIn and Twitter.

If you would like further information about how Ascentor can help improve your chances of List X success, please contact Dave James, MD at Ascentor.

Email: [email protected]

Office: 01452 881712


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Article by Paddy Keating ,Director/Government Service Manager at Ascentor.