1901–1939
In 1901, James Campbell was still in charge as proprietor and his four sons were all working for the company, including the eldest son Alexander III who had taken over as works manager on the death of his Uncle George in 1890. In 1902, the company was reorganised as a private limited company with the name Hunslet Engine Company Ltd. but was still a family business. Following the death of James Campbell in 1905, the chairmanship passed to Alexander III and brother Robert became works manager, while brother Will retained the role of secretary and traveller with a seat on the board.
At about this time, Hunslet was building a series of s for the Sierra Leone Government Railway, design elements of which were included in the construction of the famous Russell a gauge engine built for the Portmadoc, Beddgelert & South Snowdon Railway.
Following family disagreements, both Will and the youngest brother Gordon left the company and a serious injury left Robert disabled and unable to continue as works manager. The post of works manager was advertised and Edgar Alcock, then assistant works manager at the Gorton Foundry of Beyer-Peacock, was appointed in 1912. Alcock came to Hunslet at a time of change when the industry was being asked for far larger and more powerful locomotives than had ever been required in the past. This was true at Hunslet, which found its overseas customers asking for very large engines. One example was an order for two 86 ton s from the Antofagasta, Chile & Bolivia Railway.
During the First World War, overseas orders dried up. The company, like many others, found itself employing women on the shop floor and engaged in the manufacture of munitions. It continued to produce limited numbers of locomotives, significant examples being lightweight narrow gauge designs for the War Department Light Railways.
After the First World War, Hunslet was once more able to attract overseas orders and it also received a series of repeat orders from the London, Midland & Scottish Railway for 90 LMS Fowler Class 3F "Jinty" shunting engines. During the 1930s, Hunslet built its largest locomotives, two engines, built for a special train-ferry loading job in China – they were at that date the largest and most powerful tank engines ever built. A year or so later, the same design formed the basis for an 0-8-0 tender engine for India. Many other "large-engine" orders were received in these inter-war years.
Other independent British manufacturers failed to survive the depression of the 1920s and 30s and Hunslet acquired the patterns, rights and designs of other builders including Kerr, Stuart & Company and the Avonside Engine Company.
