Or I should say Canterbury Cathedral Aisle Vault Pattern Step 2?
All of the stitches used in this pattern are stitched in the backstitch/running stitch style, like blackwork, so hiding travel threads is part of the stitch technique.
Here is Step 2 of the pattern:
To travel from one vertical channel of cross motifs to another you may do one of two things: bring your thread outside of the pattern area or travel on the back, behind stitches on the front, inside of the pattern area. If the area around the pattern will be covered by another stitch, then you can hide the travel threads there. Use two pin stitches to maintain the tension after stitching one section and before stitching another section.
I would only use pin stitches if the thread lies flat, such as a stranded floss. I would not use pin stitches for metallic braids or perle cottons that are raised.
Next time I’ll cover Step 3 of this pattern.