British Battledress

Battledress was the specific title of a military uniform adopted by the British Army in the late 1930s and worn until the 1960s. Several other nations also introduced variants of battledress during the Second World War, including Australia, Canada, India, New Zealand, South Africa, and the United States of America (the E.T.O. uniform) and after the Second World War, including Argentina, Belgium, Norway, the Netherlands, and Greece.

Battledress (BD), or later No. 5 Uniform, was the combat uniform worn by British Commonwealth and Imperial forces and many Free European Forces through the Second World War. It was worn mostly but not exclusively in temperate climates. In some armies it continued in use into the 1970s. During the Second World War and thereafter this uniform was also used for formal parades (including mounting the Queen's Guard at Buckingham Palace) until the re-introduction of separate parade uniforms in the late 1950s.

From the early 1930s, the British War Office began research on a replacement for the Service Dress that had been a combined field and dress uniform since the early 1900s. Initially conducted on a small scale over several years, some of the ideas tested included deerstalker hats and safari jackets. After extensive field trials of other uniforms,Battledress, Serge (often referred to as 1937 Pattern, albeit wrongly) was adopted just before the Second World War. The uniform was designed with the needs of mechanised infantry in mind, and was inspired by contemporary wool ‘ski suits’ that were less restrictive to the wearer, used less material, were warm even while wet and were more suited to vehicular movement than Service Dress.

...
Wikipedia