What is the history of the black lanyard that royal engineers wear?

Lanyard - The Royal Engineers lanyard is navy blue and worn on the right shoulder. Since 19th century plain lanyards were used for securing the jackknife which was issued to all mounted troops. It was intended to be worn around the waist but soldiers soon found it to be more convenient to wear it on the shoulder with the knife in the breast pocket. The Royal Engineers, as did other corps and regiments of the British Army, introduced the lanyard to brighten up their battledress uniform in 1951.