Issued in cold climates, the thermal vest is used as a base layer beneath the British Army’s PCS uniform. It is made in olive green aertex type material and is a long sleeve design:

The vest is designed to be worn next to the skin so comfort is key to its design. It has a fleece lining and the seams are sewn flat so they do not irritate the skin. The aertex style outer is self wicking to remove moisture from the skin and ensure the wearer doesn’t get too sweaty. Each cuff is elasticated to help keep body heat in and improve the thermal properties of the vest:

The thermal vest has a single label sewn in with the usual details on:

Looking online there seems to be little love for issued base layers, with most recommendations being for soldiers to source their own commercial versions and if they can afford it to purchase merino wool examples in place of the issue example, although most seem to agree it is a great improvement on items issued in the 1980s and 1990s to soldiers.