Bias waistcoat question

[M. A. C. Newsome]

Matt's center stripe is green... The bias has both the green and purple...

My center stripe has the same colours as the the waistcoat...

It may be a function of the sett size/colours though...

I think it is simply a function of the fact that the tartan in the waistcoat is on the bias, and therefore there is no "center line" to match up with the center line of my kilt. However, if you look, the white line flanked by the red stripes (which is not the center line of the kilt, but the opposite pivot line to what I centered the apron to), does rather line up with those lines on the waistcoat. It's a bit askew just from the way I am standing in the photo.

However, that was purely accidental!