The 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 that was used on some early lines in England. Early railways chose their own gauge, but later in the century interchange of equipment was facilitated by establishing a uniform rail gauge across railways: the 'standard gauge' of . In the early 1840s standard gauge lines began to be constructed in Scotland, and all the Scotch gauge lines were eventually converted to standard gauge. The building of new Scotch gauge railways was outlawed in Great Britain in 1846 by the Regulating the Gauge of Railways Act 1846. From 1903, tram lines of Tokyo adopted this gauge.
A small number of early to mid-19th century passenger railways were built to Scotch gauge including:
Robert Stephenson and Company built a Scotch gauge locomotive, the St. Rollox, for the Garnkirk and Glasgow Railway; which was later sold to the Paisley and Renfrew Railway.
All the lines were later relaid in standard gauge.
In addition to the above lines, there were three railways, authorised between 1822 and 1835, that were built in the Dundee area, to a gauge of . They were:
Grainger and Miller built another two railway lines in the same area to a gauge of . Thomas Grainger is said to have chosen this gauge, since he regarded as being too narrow and Isambard Kingdom Brunel's as being too wide. They were:
The Glasgow, Paisley, Kilmarnock and Ayr Railway and the Glasgow, Paisley and Greenock Railway, which both obtained Parliamentary Approval on 15 July 1837 and were later to become part of the Glasgow and South Western Railway and the Caledonian Railway, respectively, were built to standard gauge from the start.
The Lee Moor Tramway operated a Scotch Gauge line from 1899 to the early 1960s, with the two 0-4-0ST locomotives built by Peckett and Sons to their M4 Design. LEE MOOR No.1 (works number 783) is preserved at the Wheal Martyn Museum near St. Austell and LEE MOOR No.2 (works number 784) is preserved at the South Devon Railway, neither are operational. Both locomotives were originally preserved by the Lee Moor Tramway Preservation Group.
The standard gauge of , also known as the Stephenson gauge after George Stephenson, was adopted in Great Britain after 1846 after the passing of the Regulating the Gauge of Railways Act 1846. A few remnants of old lines remain, but are non functional with the exception of one example of the St Michael's Mount Tramway at St Michael's Mount in Cornwall. It is a partial underground railway that used to bring luggage up to the castle. It occasionally operates, but only for demonstration reasons and is not open to the general public, although a small stretch is visible at the harbour. It is therefore believed to be Britain's last functionally operational Scotch gauge railway.
After the end of the Scotch gauge in Britain, the gauge was revived in Japan. Its origins date back to the Tokyo Horsecar Railway, one of former horsecar operators in Tokyo, adopted gauge in 1887. Since 1903, most of the tram network in Tokyo was built with rail gauge, called . The use of this gauge extended to other suburban lines that through-operated onto the city tram network. Although Tokyo has abolished its major tram network (except the Arakawa Line), as of 2009 the following lines still used this gauge: