In 1911, Robinson designed his Class 8K as a heavy freight locomotive for the Great Central Railway. Around half of the 126 locos were built at the company's works at Gorton and the rest were built under contract by Kitson & Co. and the North British Locomotive Co.

As the First World War progressed, more powerful locomotives were required on the Western Front and no design was more suited to these needs than Robinson's new 2-8-0. As a result, 521 were constructed for the Ministry of Munitions between 1917 and 1919, the work being undertaken by a number of contractors.

At the end of the war, the government offered the locos for sale and the GCR bought 3, the GWR 20 and the LNWR 30. Many of the rest were loaned out until the winding up of the ROD in 1921. They were then sold at bargain prices to get rid of them and the LNER bought 273, the GWR a further 80 and the LMS a further 75. The rest went to China (24) and Australia (13). The LNER locomotives, including those inherited from the GCR, were reclassified as Class O4.

Some were again requisitioned by the War Department in the Second World War but 329 of the class (including a variety of 'rebuilds') were taken into BR ownership in 1948. Despite their age, some survived in Britain until 1966 and one has been preserved. Three of the batch sold to Australia have also survived.