The common case for stories like this is the answer is "nobody."
Time point 1: "We need a way to map the long-form epidemiology state. It's 2D data... Let's use Excel." "Will we hit limits?" "Pfft, no. Not unless we end up needing to track tens of thousands of patients, and that's not practical; we don't have enough people to do that tracking in the whole NHS."
Time point 2: "This pandemic is an URGENT problem. We need to hire more people than ever before to do tracing. And be sure to keep the epidemeology state mapper updated so it can drive the summary dashboards!"
Time point 1: "We need a way to map the long-form epidemiology state. It's 2D data... Let's use Excel." "Will we hit limits?" "Pfft, no. Not unless we end up needing to track tens of thousands of patients, and that's not practical; we don't have enough people to do that tracking in the whole NHS."
Time point 2: "This pandemic is an URGENT problem. We need to hire more people than ever before to do tracing. And be sure to keep the epidemeology state mapper updated so it can drive the summary dashboards!"