Back-stitched chain stitch
This stitch is, as its name suggests, a combination of back stitch and chain stitch. Having stitched a line of chain stitch, a line of back stitch is then stitched over the top: each stitch starts and ends in the centre of each loop of chain.
Structure of stitch
Mrs Archibald Christie, Samplers and Stitches (1921) , p.42