Southdown Motor Services can trace its history back to a pair of steam buses which operated between Pulborough and Worthing. However the company itself was formed in 1915 abandoning plans to call itself South Coast Motor Services (a similar name had been registered by a Folkestone operator). BET took an early interest in the company as well as Thomas Tilling. The original registered office was in Middle Street, Brighton and in 1916, a garage was built in Freshfield Road. The operating area of the company was bounded by Eastbourne, Portsmouth and the Sussex border. In 1921, joint services with Maidstone & District were started between Brighton and Hawkhurst (later service 18) and Eastbourne and Hastings via Hailsham (15). Similar services to Southampton and Winchester (joint with Hants & Dorset) began in 1922, although the Winchester service was truncated at Fareham in 1926. Horsham marked the boundary with Aldershot & District, Southdown later abandoning its operations in Haslemere in favour of the Aldershot company. Southdown also began to establish a programme of local long distance tours throughout the twenties and it was in 1921 that the famous Southdown scroll logo was adopted. Southdown pursued a policy of purchasing rival operators to consolidate its business. Companies acquired included Royal Red Coaches of Hove and Eastbourne operators Foard's, Cavendish, Southern Glideway and Chapman & Sons.