In the 1920s underground, trains for the District line were manufactured and trains for the Piccadilly line and Hammersmith & City line were made in the 1930s. The firm began manufacturing all welded wagons in 1935, as well as manufacturing the bodyshells for GWR railcars. In 1936 the firm won the contract to build a 68 feet long air-conditioned carriage for the Maharajah of Indore to be designed by a German architect and to include a kitchen, servants quarters and a nursery. By 1937 the firm had a site including a 980 kW electricity generating station, and employed 2400 people.