It appears the previous owner added a keen hand at sewing and added an extra internal pouch

Waist Size: 42" | Suggested Size: X Large Regular

It went onto inspire numerous patterns over the following decades

Pit to Pit: 20" | Suggested Size: Medium Slim - Label suggests a chest around 100cm

British Army / Tri-Services Navy Blue PTI Shorts - W32 Swiss It appears the previous ownerAt a glance Polyester & Cotton Blend Material 2 Waist Pockets & 1 Rear Zipper Closure Hook & Eye Waistband Pleated Design Button Waist Adjusters 1" Belt Loops Solid Navy Blue Colour Waistband Flat: 16" Suggested Size: Small Slim Label states 86. 5cm Total Length: 17" Modern Militaria Issued 1994 2003 Genuine British Royal Air Force, Army & Royal Navy Surplus Grades Grade 1 Good condition, some prior use. May benefit from a quick iron but up for plenty