This pot was sold at the Warren and Wignall auction on 8th February 2017.  It caught my eye because I hadn't seen this glaze before, and now it's mine, it still remains something of a mystery, at least to me.
It's marked as shape number 291, has the CSA Ltd stamp (so dates from 1925 to '34) and has a painted number 1, that must refer to the glaze.  It has a red body, that I think is more highly fired than the usual earthernware body and has a thick glaze.  Both the body and glaze have been ground down on the base as you find on the chinese blue vases.
If anyone has any more insights I would be glad to hear from you.