Introduced at the turn of the century, Service Dress replaced the red tunic for field use. Prior to this, there had been no universal temperate field uniform. Though khaki uniforms had been in use for several years before this, they were generally only used in hot climates - temperate field wear being of regimental pattern: red, blue, rifle green etc.
The introduction of Service Dress saw regimental pattern uniforms being relegated to Full Dress usage only, though dress uniforms were still on general issue up until the First World War.
SD comprised a khaki high-collared, four-pocket jacket and trousers manufactured from hard-wearing woollen serge. The uniform came with a khaki peaked cap made from the same materiel and woollen puttees were worn in the field.
The practicalities of this arrangement over its predeccesors were instantly apparent, the uniform being generally well received. The use of a universal ORs uniform certainly made supply and issue easier than before.
This is the uniform worn throughout the Great War and beyond before its replacement by Battle Dress, though it continued to be worn by certain non-front line units in to the 1950s. The GMS is a direct descendant of Service Dress. Imagine having to fight in your 2s and puttees?
Officers' Service Dress was different. Of superior manufacture and cut - and worn with collar and tie - it is still in use today, albeit with slight changes to the style.