At age 18 in September 1911, he began work as Alliott Verdon-Roe's (later Sir Alliott) personal assistant and the firm's draughtsman at A.V. Roe and Company, Avro, based at Brownsfield Mill, Manchester. Under the direction of A.V. Roe, Chadwick drafted the Avro D, a two-seater tractor biplane, the Avro E, which was converted to a floatplane, and in 1912, the Avro F, the world's first monoplane and cabin machine. He then worked on the draughtsmanship for the Avro 500, 501 and 503, which led to Avro's World War I light bomber and trainer, the Avro 504.