I picked up this standard size Victorian salt recently. It is unmarked. It has a density value consistent with a Northwest or Midlands manufacturer, so we can rule out the northeast, and I would guess dates to the 1870s. In looking around for a matching pattern, I note that the Pottery Gazette article detailing Joseph Webb's pressed pieces being transferred to Edward Moore in 1888 shows a similar design on a pickle, sugar etc - of four diamond panels separated by these clear ridges.
Joseph Webb of Stourbridge is my current favoured attribution, any other views?