The Data Support Service project of the UK Medical Research Council (MRC DSS) developed a Research Data Gateway to enable the deep discovery of MRC-funded population and patient studies and their datasets and variables. The Gateway enables researchers to find and explore variables across longitudinal cohort studies, to support data linkage for new research. A federated approach is used, whereby studies are responsible for storing, preserving, curating and disseminating data; publishing standardised metadata into the gateway. The system uses a Drupal content management system and Apache solr search and browse functionality, with metadata organised into modular units representing studies, time periods, collection events and variables. Users can search and discover variables across studies and export baskets of variables to request access to data. The directory holds over 45,000 variables for four case studies: Avon Longitudinal Study of Parents and Children (ALSPAC), National Survey for Health and Development (NSHD), Southampton Women's Study (SWS), Whitehall II. Variables for a further ten cohort studies are being incorporated. Development towards a DDI3.1 metadata exchange standard is ongoing, enabling metadata from diverse formats and structures to be ingested into the gateway. MRC DSS also works closely with research units towards integrated data management planning.