Sunbeam was part of the Sunbeam-Talbot-Darracq combine which was taken over by Rootes in 1935.
The first Rootes Sunbeam is designed by Georges Roesch as Rootes' flagship. A new 4503cc straight eight engine is designed for the Thirty. It develop 150bhp at 4500rpm. A four speed gearbox is fitted, without syncromesh on first. The chassis is based on that of the large Humbers. It appeared at the Olympia Motor Show in 1936. It was then decided not to put the Thirty into production. The four cars built were all broken up.