eBay
Here we have the latest issue lightweight combat shirt, part of the new Personal Clothing System (PCS) being introduced as the standard combat uniform for all UK forces.

This is the temperate issue version, made of slightly heavier weight fabric for use by troops in the cooler UK climates!
 
Zip and velcro front with central rank eppaulette, two large chest pockets accessed via velcro vertical openings (pen slots inside), and button adjustable cuffs.
Upper arms feature large box style cargo pockets complete with velcro insignia panels to which rank insignia, unit badges can be added. These panels can then be easily removed in a combat situation, or switched to another garment such as smock or UBACS shirt as desired to suit the clothing being worn.
Mandarin style velcro collar which can be worn in the up position with armour vests or folded down flat for smarter general appearance.
 
This example here is a 170/96 size, suitable approx for someone 5'7 - 5' 9" in height , with a 38 -41" chest.
 
Brand new unissued condition, still in poly wrapper..