John stitch
John stitch is made up of blocks of Tent stitch and Reversed tent stitch with a long slanted stitch separating them.
Method
1
First work three tent stitches in a vertical line.
2
To the left of these, work three reversed tent stitches (tent stitches which slant from top left to bottom right) to make a rectangular block.
3
Beneath this block make a stitch across two by one threads of canvas from top left to bottom right.
4
Repeat this group in vertical rows.

Embroidery Techniques
Identifying John stitch
A repeated pattern of one line of three tent stitches alongside one line of three reversed tent stitches, followed by a long slanted stitch (across two by one canvas threads).
References
-
Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.113