Access to the large majority of micro data only requires registration, agreement to an End User Licence (EUL) and the registration of usage details. These data are fully anonymised and certain variables may be suppressed to minimise the risk of disclosure.

However, it is recognised that some researchers need access to more detailed data. To facilitate this and to increase the range of data available for statistical research, the Office for National Statistics (ONS), in collaboration with the UK Data Archive (UKDA) and ESDS Government, developed a Special Licence (SL) to provide access to social survey datasets that are detailed, yet anonymised. The SL was launched in September 2005.

The coming into force of the Statistics and Registration Service Act in April 2008 brought an end to the SL arrangements. Access to ONS SL data continues but under a new legal framework set out in the Act. From April 2008, any registered user requiring ONS SL data has to be accredited by the UK Statistics Authority as an Approved Researcher. Users can order data from UKDA/ESDS in the usual way and will be directed to the Approved Researcher forms for completion.

To apply for accreditation a user must complete forms that require:

1. evidence that he/she is a fit and proper person and details about the purpose of the research
2. an online order for the data
3. a signed declaration that he/she understands the confidentiality obligations owed to those data including its physical security

The evidence to be adduced includes previous research projects and publications. New users may need to provide the contact details of a senior member of staff who can vouch for them. The research purpose form asks for information about the intended use of the data, a justification for access and planned outputs.

Users who obtain access to SL data are required to read and follow the Guide to good practice: micro data handling and security. This includes additional guidance on:

• avoiding inadvertent statistical disclosure
• storing and accessing data securely
• how to permanently destroy copies of data

The following government SL datasets are available:

• Annual Population Survey: Special Licence datasets
• Family Resources Survey: Special Licence datasets
• Quarterly Labour Force Survey: Special Licence datasets
• 2001 Census: Special Licence Household Sample of Anonymised Records (SL-HSAR)

ONS intends that all social survey datasets will continue to be deposited in a form suitable for use under the current EUL. ONS does not intend to review the status of datasets deposited before June 2005 and currently available under the EUL. This does not rule out the possibility of additions to the UKDA of SL versions of these earlier datasets.

Other depositors, including the Centre for Longitudinal Studies are continuing to use the original SL form and intend to move over to a similar arrangement to Approved Researcher access. Other data available include:

• 1970 British Cohort Study
• Millennium Cohort Study: Special Licence datasets
• National Child Development Study
• British Household Panel Survey: Conditional Access
• British Household Panel Survey: Special Licence Access

Versions of these datasets that contain more detail are clearly marked as 'Special Licence' datasets. Users will be directed to the relevant forms during the ordering process.