Siddeley Aircraft was a British aircraft manufacturer founded in the early 20th century. It became known for producing a variety of military and civilian aircraft, particularly during and after World War I. The company was involved in several significant aviation projects and contributed to advancements in aircraft design and technology. In 1920, Siddeley Aircraft merged with Armstrong Whitworth to form Armstrong Siddeley, which continued to produce aircraft and engines. The company played a crucial role in the development of several notable aircraft, including the Whitley bomber and the Siskin fighter. Siddeley Aircraft's legacy is part of the rich history of British aviation.