Quaker stitch

Quaker stitch is a stem stitch that has been combined with a split stitch to anchor the thread as it turns corners.
It was specifically developed to produce clear and defined lettering on the Quaker Tapestry, a twentieth-century crewelwork piece that documents the history of Quakerism.
Method
Bring your needle to the surface at the top of your marked line, then take the needle down through the fabric further along the marked line to make an initial stitch.
Bring the needle up again in the same hole as the initial stitch.
Push the needle down through the fabric one third longer than the first stitch. Draw the thread through, leaving a small loop on the left.
Keeping the loop on the left, bring the needle back to the surface, splitting the initial stitch in its centre.
Pull through the slack on the loop with your underneath hand and draw the needle and thread to the surface.
Repeat from step 3, bringing the needle up two-thirds of the way through the previous stitch, and then continue along your marked line to the end.

Structure of stitch
Common uses
Embroidery Techniques
Related Stitches
References
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Jacqui McDonald, RSN Essential Stitch Guides: Crewelwork (2010)
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Various Authors, The Royal School of Needlework Book of Embroidery (2018) , p.61