Thank you so much. Find and Replace is so powerful in Calibre! Apply changes to all files making up the book - that is so useful!!
Once I'd got familiar with the wild card terms and the Find and Replace section of the editing page, I was able to clean up the book in very little time.
It
was a pdf file, which I wanted to read on my Kindle. Pdfs are a bit clumsy and inflexible when displayed via the Kindle app (no font size control for one thing), but a bit of cleaning up (yes there were other errors which I did correct - well probably most of them) and converting to Amazon file format made the book much easier and more pleasant to read.