Thanks PeterT, that did the job of not over-writing the read status in the Kobo Touch.
Is anyone aware of how to sync this status between Calibre and a Kobo Touch. I keep reading snipets about "Im_reading", "Read" and "Closed" tags but am not sure how to use this. Can someone post a method (in detail) please. I assume that these are Calibre tags that are linked to equivalent field values within the Kobo. Or are these keyword tags that go in the Tags field.
Calibre really needs another word other than tag. There is the 'Tag Browser', 'Tags' field and XML like 'tags' used in filters and headings. All of these are completely different and makes it hard to follow short instructions offered in forums like this one.