Thanks, I'll look for that next time. The problem with Excel and these CSV files was it mangled the date column, which I only found out about after a bunch had been fully edited. I used modern CSV to rescue this and so have been suspicous of going back to Excel to do any further manipulations.
The good news is PowerQuery has data types! Although it is not as flexible in editing particular records if that is a requirement (just bulk edits, joins and merges)