If you read the article (perhaps its been updated?), they were using the old XLS format and they hit the limit at 64,000 lines
PHE had set up an automatic process to pull this data together into Excel templates so that it could then be uploaded to a central system and made available to the NHS Test and Trace team as well as other government computer dashboards.
The problem is that the PHE developers picked an old file format to do this - known as XLS.
As a consequence, each template could handle only about 65,000 rows of data rather than the one million-plus rows that Excel is actually capable of.
If somebody finds it easier to do this process using Excel than with a scripting language, I wouldn't expect them to know the differences between file formats. I would be surprised if they understood the concepts behind file formats.
They may have chosen XLS because they used Excel back when that was default, and now they don't want to "risk" anything by switching horses mid-stream.
PHE had set up an automatic process to pull this data together into Excel templates so that it could then be uploaded to a central system and made available to the NHS Test and Trace team as well as other government computer dashboards.
The problem is that the PHE developers picked an old file format to do this - known as XLS.
As a consequence, each template could handle only about 65,000 rows of data rather than the one million-plus rows that Excel is actually capable of.