The twin-engined British Aerospace BAe 125 is the world's best selling mid-size corporate jet, with newer variants now marketed as the Hawker 800. It was known as the Hawker Siddeley HS125 until 1977. , The twin-engined British Aerospace BAe 125 is the world's best selling mid-size corporate jet, with newer variants now marketed as the Hawker 800. It was known as the Hawker Siddeley HS125 until 1977.