Unitrade has examples of two constant varieties, SC 532i "blue throat" and SC 532ii "The seven sisters", positions 36 and 39 respectively.
As I have not requested permission to use the catalogued scans, I have included only a copy of the original stamp with arrows indicating the positioning of the blue throat and seven sisters markings.

I have two full inscription selvage-removed field stock panes of this issue and neither have either of these identified-by-position varieties. My panes have wider top and bottom selvage compared to the very narrow left and right sides. It is not possible to determine if they are UL, UR, LL, Or LR panes.
Does anyone have an UL, UR, LL, or LR pane (inscription or other) with the two varieties.
I'm wondering if these two varieties are truly "constant" and worthy of inclusion in catalogues as a listed variety.