Seems like other (slightly) more reputable sources are now reporting that it's Excel: https://www.standard.co.uk/news/uk/covid-testing-technical-issue-excel-spr

Seems like other (slightly) more reputable sources are now reporting that it's Excel: https://www.standard.co.uk/news/uk/covid-testing-technical-issue-excel-spreadsheet-a4563616.html https://www.standard.co.uk/news/uk/covid-testing-technical-i... A Telegraph article mentions a Press Association report.