Welcome to UK LLC

Welcome to UK LLC#

Last modified: 03 Feb 2026

Guidebook is the home of UK Longitudinal Linkage Collaboration’s data documentation and user guide.

UK LLC is the national Trusted Research Environment (TRE) for data linkage in longitudinal research. UK LLC brings together de-identified data from Longitudinal Population Studies (LPS) and links these data to study participants’ health, administrative and place-based records in the UK LLC TRE.

UK LLC’s published protocol paper explains how UK LLC works. Currently, researchers can request access to data from >20 LPS. Participants’ records are linked to NHS England and place-based datasets wherever participant permissions allow.

UK LLC’s unique attributes include:#

  • The dynamic nature of linkages. Linkages to NHS England datasets are refreshed every 12 months, and we can provide researchers with access to new or updated LPS datasets as they become available, ensuring the temporal alignment of LPS and linked data.

  • The consistent nature of linkages. All linkages, data extracts and post-processing are done in the same way, at the same time, across all LPS. This facilitates cross-study analysis as data are directly comparable.

  • The breadth of data types. UK LLC already contains data collected by LPS from across the four UK nations, data from NHS England, and place-based data. In 2026, data from NHS Wales, NHS Scotland, the Department for Work and Pensions (DWP), and HM Revenue and Customs (HMRC) will be uploaded into the TRE (see Next steps for UK LLC below).

  • The range of linked health records. UK LLC has the maximum number variables permitted by NHS England, across a wide set of linked health records, covering primary, secondary and community-based care.

  • A dynamic library of research products. Reusable syntax and derived variables are developed by UK LLC researchers and made available to all TRE users.

  • Harmonised variables. Sex, gender, ethnicity, year of birth and education have been harmonised across all partner LPS, so researchers can quickly understand the socio-demographic makeup of their study population.

  • The simplicity of the application process. Researchers complete just one form to apply for LPS or linked data. Researchers already working in the UK LLC TRE add additional data as it becomes available, via UK LLC’s amendment process.


Please visit:
UK LLC Explore (UK LLC’s metadata catalogue) to discover the breadth of data held in the UK LLC TRE.
UK LLC Apply (UK LLC’s online application management system) to apply to access data.

Next steps for UK LLC#

Data#

  • Increasing the number of partner LPS: Many more UK-based longitudinal population studies (LPS), or cohort studies, are joining UK LLC and making their linked data available to researchers.

  • Maximising data availability: Current partner LPS are continuing to add to the resource by depositing new and back catalogues of datasets.

  • Increasing the number of place-based datasets: There is a growing number of place-based datasets available to complement the LPS and linked data. In 2026, these will be expanded to include data on climate variables and mobility.

  • Health data: Welsh and Scottish health data will become available in 2026. Discussions are underway to link Northern Irish health records.

  • Non-health administrative data: data from the Department for Work and Pensions (DWP) and His Majesty’s Revenue & Customs (HMRC) will be available to request in 2027. Negotiations are underway with the devolved UK authorities regarding access to education data.

  • Genetics / ‘omics’ data: Many LPS collect genetic and ‘omics’ data about their participants. Some of these data are already available as summary variables. Storage and analysis of omics data requires expansion of the TRE’s capacity and technical capabilities. Omics research will take place in Linux Virtual Machines (VMs) connected to a High Performance Computing (HPC) facility and to dedicated object storage. UK LLC will soon be running a series of pilot projects to test the feasibility of a new HPC infrastructure for linked omic analysis.

  • Synthetic data and a novel training resource: A training secure data environment (t-SDE) is being developed with our partner SeRP, to replicate UK LLC’s existing TRE functionality. The t-SDE will contain synthetic (artificially generated) data, that resemble the real LPS and linked data, in a dedicated virtual learning environment. This will be complemented by training materials to assist researchers with navigating the UK LLC resource and underlying data.

Access#

  • Access to researchers outside the UK: Currently only UK-based researchers can apply to access data. Work is underway to enable access for researchers in some other countries where participants have given their permission.

  • Commercial organisations: currently commercial organisations cannot apply to access data held by UK LLC. In the future some commercial organisations may be able to apply to access data for specific not-for-profit purposes where participants have given their permission.

    Before changes to access are made, thorough consultation, governance and policy considerations will be undertaken, particularly with LPS and the public. Access for researchers based in some countries outside the UK, and in some commercial organisations, may be possible by the end of 2026.

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