Using the same boiler, valve gear, trailing axle and other assemblies as the WP class Pacific locomotive built from 1947, the WG class Mikado was built from 1950 onwards. In order to be able to produce the quantities required for widespread use in front of freight trains, production was initially divided among several manufacturers in different countries.

The first 100 units came from the North British Locomotive Company in 1950. Later more came from there, others from the Vulcan Foundry, as well as from Belgium, Germany, Italy, Austria, the USA and Japan. Large-scale production only gradually got underway at the Chittaranjan Locomotive Works in India. Since, unlike at North British, they did not yet have the means to manufacture such a large three-shot boiler, the boiler was initially made with four shots. It was not until 1956 that production could be carried out completely in India, so that by 1970 a total of 1,908 of the 2,450 machines in total were built there.

The last WG built was also the last broad gauge steam locomotive built in India. In a nod to the last standard gauge Class 9F steam locomotive “Evening Star” built in Britain, it was called “Antim Sitara”, which has exactly the same meaning. The “Antim Sitara” is one of the nine that still exist today. Another, built in 1964, is still operational today.