Source: THOMAS, Mary (1934). Mary Thomas’s Dictionary of Embroidery Stitches, London: Hodder and Stoughton, pp. 120-121.
GVE
The threaded herringbone stitch is a variation on the herringbone stitch, in which a second thread is threaded (laced) upwards and downwards through the foundation stitches (in this case the herringbone stitches). The threading yarn does not penetrate the ground material and is usually in a different colour from that used for the herringbone stitch.
Source: THOMAS, Mary (1934). Mary Thomas’s Dictionary of Embroidery Stitches, London: Hodder and Stoughton, pp. 120-121.
GVE