I have a friend I consider an expert knitter who thinks seed would behave along the lines of garter stitch and, so there would be less stitches to an inch compared with stocking stitch.
That fits in with the pattern I was wondering about. The yarn it calls for is 18 st/4 inches in stocking stitch, but the pattern stitch for gauge is seed at 16 st/4 inches.
My dilemma is that I want to use yarn which is 16 st/4 inches in stocking stitch. I am knitting a 'Maggiknits' pattern which calls for Maggi's Tweed Fleck Aran (18/4). I want to substitute Rowarn Yorkshire Tweed Aran, which is 16/4. It is not a pattern to be mucked about with, so I can't just make it smaller. I guess I will use smaller needles than called for and hope to get away with it!