The core data platform for NHS Test and Trace was not Excel based at all. It was a reasonably simple but solid AWS setup using S3, Glue and the smallest Redshift instance at the time, on top of which were Tableau/Quicksight/PowerBI dashboards. Some organisations insisted on enabling an "export to CSV" feature which was...not a good idea for so many reasons, and Public Health England (PHE) in the article found out one of those reasons the hard way.