Building a city-scale data service for better care, research and planning

London’s health and care system runs on many systems and standards, “deep data” lives across GP, acute, community and mental health settings, with several different EPRs in use by providers. To plan services, reduce waiting lists and enable research, the capital needed a single, secure, standards-based way to bring data together at population scale.

We were commissioned to help design and build the core data service for OneLondon:

1. Ingest and harmonise GP data from EMIS (via IM1) and TPP (via the TPP gateway) into a common data model for London.
2. Publish back to each ICS via secure, controlled access (now Snowflake), providing consistent, well-coded data products for analytics and planning.
3. Flow into the London Analytics Platform, the part of the London SDE infrastructure for research, to enable secure research at scale across primary, acute, community and mental health datasets as they’re onboarded.
   
   

As trust grew, our role expanded beyond engineering into programme planning, service readiness, and wave-two roadmap support to help OneLondon deliver and transition the service safely into BAU.

London-wide pipeline for trusted primary care data

• Multi-source ingestion: EMIS via IM1 and TPP via the TPP gateway, with lineage and provenance tracked end-to-end.
• Standardisation and coding: Normalisation, SNOMED concept mapping and a common model so every ICS receives consistent, analysis-ready data.
• Secure distribution: Publication through Snowflake locks into each ICS’s subaccount; LDS also publishes to other areas of the London SDE so researchers can work on de-identified, standardised data.

ICS analytics teams use LDS data to power planning and improvement, from waiting list intelligence to risk stratification and long-term condition management.

At London level, the SDE brings together primary care, acute , mental health and community datasets so researchers can run approved projects on a common, well-governed foundation, with feedback loops that convert models into real-world impact.

For clinicians and patients, joined-up, high-quality data enables safer, faster, more personalised care and helps reduce unwarranted variation across the capital.

For ICS leaders, a single source of truth for primary care, soon extending to community and mental health, underpins planning, performance, and pathway improvement. And for researchers, secure access to rich, standardised datasets accelerates discovery and evaluation on London-scale cohorts.

OneLondon is creating one of the UK’s most ambitious, secure, and standards-based health data services. Answer Digital is proud to be the partner delivering the engine that unifies London’s data, moving the system from fragmented records to trusted, actionable insight for care, planning and research at true city scale.