In the years prior to the First World War the Pelican Yard was built up and used for the assembly and testing of petrol engines for rollers and lorries. On the outbreak of war petrol work stopped and the works were used as a store. Although concentrating on steam rollers (for which there was an expanding market), the company also made traction engines, ploughing engines, steam wagons and tramway locomotives. Other agricultural products were contracted out. In the early twentieth century Aveling & Porter were supplying about 70% of the British market for road rollers.