British Army cold weather clothing works on the layering principle, which was originally pioneered by the US Army in the Second World War. The basic principle is that multiple thinner layers of clothing are more effective at keeping the wearer warm than one thick layer because a small pocket of air gets trapped between each one that then warms up and helps keep the wearer protected from the cold. The base layer of the British Army arctic clothing set was and remains a pair of long-john type cold weather drawers. These are made of a dark green cotton and cover most of the wearer’s legs:Like a pair of Y-front underpants they have a separate gusset over the crotch to ensure there are no seams at this potentially uncomfortable spot:A light grey-green elastic waist band secures the drawers at the top:Whilst the bottom of each leg is also drawn in to help trap the layer of air within the garment:A standard label is sewn into the back of the waistband of the drawers, in this case quite badly faded:Six different sizes of this garment were produced, as can be seen in this extract from the store’s catalogue: