Welcome to UK LLC

Welcome to UK LLC#

Last modified: 06 Feb 2026

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

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

A published protocol paper explains how UK LLC works. Currently, researchers can request access to data from 22 LPS. Participants’ records are linked to NHS England and place-based datasets wherever participant permissions allow.

UK LLC is unique because:#

  • Linkages are dynamic. 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 nature of linkages is consistent. 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#

Over the next year, UK LLC is planning to:#

  • Increase 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.

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

  • Increase 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.

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

  • Make non-health administrative data available: data from the Department for Work and Pensions (DWP) and His Majesty’s Revenue & Customs (HMRC) will be available to request towards the end of 2026. Negotiations are underway with the devolved UK authorities regarding access to education data.

  • Expand capacity to include 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.

  • Develop 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.

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