The class I consisted of 31 0-6-4T tank locomotives built by three British manufacturers between 1907 and 1916. They had driving wheels with a diameter of four feet and four inches (1,321 mm) and cylinders of 14.5 by 20 inches (368 by 508 mm). The first five were built with 800-gallon water tanks by Kitson in 1907 and 1908, followed by three more from North British in 1912. Kitson delivered 18 more in 1913 which had tanks with a total capacity of 1,200 gallons. The last five came from Hawthorn Leslie in 1916.
Originally, they carried non-consecutive numbers. The first 13 were withdrawn between 1927 and 1940. In 1946 they became class 301, numbered 301.01 to 301.18. All were withdrawn between 1949 and 1953. In 1951 and 1953, one locomotive each was sold to Malayan Collieries.