The Southern Railway inherited a range of railway-related activities from its constituent companies, which it continued to develop until nationalisation in 1948. These activities included several ports, a fleet of ships, road services (both freight and passenger) and several hotels. These ancillary operations provided extra revenue for the railway at a time when railways were classified as a common carrier by the Railways Act of 1844, and could not compete with road with regards to pricing. This was because railways were obliged to advertise their rates of carriage at railway stations, which could subsequently be undercut by road haulage companies. The Southern Railway also invested in an air service during the 1930s, which supplemented the popular sea crossings to the Isle of Wight and the Channel Islands.