It was relatively easy to put in the first row of threads. I put the lines two threads apart - easier to see than the single thread of the original mending stitch. The even-weave linen helped.
Couching down the thread intersections, is however, a bit trickier. Here I have only couched down the top tips and the lower left - but developed a bit of a curve in the latter. By working two threads apart for the original rows, I gave myself a bit of a challenge in couching in small spaces.
From a distance, he looks as if he is wearing gingham, or checks. It will be quite a hard-wearing stitch, and worth the experiment, but it isn't a stitch I am going to use again on this project now I have the darning stitch under control.
I have applied the darning stitch to the rest of Lattice Man - with my magnifiers I can work a proper running stitch!