Why is a copy of the data stored in BC|Link?

It is a core data protection concept to minimise data. CO-CONNECT has not specified what data each Data Partner must make discoverable. Each Data Partner goes through a process to determine what data should be made discoverable via the HDR UK Cohort Discovery Tool. It also ensures this software can be isolated from the wider network, so it only stores what the Data Partner decides is relevant. BC|Link can also only connect to outside servers or other internal systems that the Data Partner deems to be necessary. The software is always stored in the environment of the Data Partner and is always under their supervision.