Panic over - lesson learned from a Google Spreadsheet

Let me set the scene - questionnaire out to all staff on which committees they want to serve on, received on a Google Form, then editing the Google Spreadsheet formed by the answers (including the datestamp information).
It needs a little tidy-up, of course, let's get rid of the datestamp and responder information that was automatically gathered by the form, then share it to all staff....
Spreadsheet disappears and this message appears, for all who access it:

Now, we really needed this information but it was gone!
We had many e-mails back from staff saying that they could not access the spreadsheet, not from home nor from school. Panic!
We contacted Google Enterprise Support the next day and had an instant reply from Eibhin Martin. At least we felt supported.
There were questions to answer and we shared Eibhin into the spreadsheet.
Later, quite by chance, JS found that she had the document open in one of her hundred tabs or so which are habitually open on her computer, and we were able to see a version of the committee lists - phew!
Eibhin got back to us - not a good idea to edit spreadsheets formed from forms - corruption of either or both can be the result.
Lesson learned. We shall make a copy in future before messing with it...