Also, as I look at the diagram in the book (not a photo but a drawing), it looks to me as though when the right needle is inserted into the row below, it must also sort of be going through the bottom of the actual stitch on the left needle; in other words, the bottom of the first stitch on the left needle as well as the top part of the row-below stitch, the one that is actually being knit into.
Well, if that's true, then why did she state that the stitches would fall off? If you stitch through both the current stitch and the one below it, then that would, effectively secure the stitches and prevent them from falling off.
I must have an earlier version of the book than you do; my borrowed copy as a picture of the author on the cover. The illustration definately shows the needle going through only the lower stitch. I'll look again to see if it says anything about a foundation row.
The author does, however, state that this stitch is often used in fisherman's sweaters. It deceptively looks like ribbing, but is not and is more tedious to do than ribbing.
The pattern is from an Italian knitting magazine. Filatura di Crosa #29. The double-stitch is the first four rows after casting on and then ribbing follows it.
I'll put in a foundation row on a test swatch (knit or purl) and see how it turns out. Thanks for your input!