The 4 ft 6 in (1,372 mm) track gauge, also called the Scotch gauge, was adopted by early 19th century railways mainly in the Lanarkshire area of Scotland. It differed from the gauge of 4 ft 8 in (1,422 mm) that was used on some early lines in England.

The 4 ft 6 in (1,372 mm) gauge, historically known as "Scotch gauge," was a regional rail standard adopted primarily in 19th-century Scotland for early passenger and coal lines like the Monkland and Kirkintilloch Railway. While most of the world eventually transitioned to the "Standard Gauge" (4 ft 8.5 in), this specific measurement surprisingly found a second life in Japan. Known there as "Coach Gauge" (Basha Kikan), it was adopted by the Tokyo Horsecar Railway in 1887 and later became the standard for Tokyo’s extensive tram network. In 2026, it remains a functional oddity; while most Japanese railways use 1,067 mm (narrow gauge) or 1,435 mm (standard gauge), the Keio Line, Toei Shinjuku Line, and the Toden Arakawa Line in Tokyo still operate on this 1,372 mm gauge, a lasting legacy of the city's early 20th-century urban transit design.