Vtg 1978 XL/XXL Red Green Black Tartan Wool Pants 
High waist. 
Flat Front, Straight Leg
Unlined. 
Two side slit pockets and two back welt pockets. Back left pocket buttons shut. 

Faded tag looks like a 1960s/1970s ACWA/ACTWU Union Label.
The tag indicates: "Scottish Modern, D. Lothian 3529. 6-78." (Possibly made in 1978?). 
I was unable to find any brand information. 

Great condition! No rips, stains, or snags. 
There appear to be two small repairs on the seams (vertically) above the back pockets (Photos 17-18.)
The left back pocket can be buttoned closed inside and the button looks like a replacement.

Size 36x31 (Approximately modern XL/XXL or size 16 or 18). 

Lay Flat Measurements in Inches
Waist18Inseam31
Waist (Stretched)18.5Thigh14
Rise14.5Knee10
Hips25.5Ankle/Leg Opening10.25
Hips (Stretched)27.25

All items are being sold from a non-smoking, pet-free home, but were sourced second-hand. I have no knowledge of their history.

See photos for measurements and item condition.
Hanging photos are in natural light. All other photos are in artificial light.
All measurements are approximate.
Colors may vary based on lighting, monitor resolution, etc.