The stitch is a simple treble or double crochet as the Americans would say. I can't believe I ever did this. There is no way I would take on something of this size again. Those rows are quite long - 300 stitches across, and 164 rows of 10 up, 2ch, 10 down, miss 1 and then up again. The zig zag ripple gives the fabric a bit of stretch. This rug used to be a favourite for sleepovers when the kids were little. Now it is stuffed in a cupboard. I am sure it will have a few more days of glory if I hang onto it.
It is worked in 5 ply yarn which is hard to come by now, and double knit or 8 ply seems to have taken over.
Any hoos thanks for looking!