designs such as the King Arthur, Schools and Lord Nelson classes, and later the Bulleid Pacifics, as well as the expansion of the electrified third rail system from suburban roles (a system which had replaced the LB&SCR overhead electrification, which in turn had replaced the role of the D class tanks on suburban traffic from around 1910), the company was not concerned about replacing the veteran tank engines on branch line workings, especially as many of the smaller branch lines were not economically viable for electrification, or were isolated from the rest of the electrified network. As a result, the Southern Railway felt that perseverance with the older locomotives such as the A1X on rural routes was the most economically viable option. British Railways (1948-1963) At nationalisation in 1948, one "A1" and 14 "A1X" locomotives entered British Railways stock. All but one of these locomotives were based on the former Southern Railway, which became the Southern Region under British Railways, with the other based on the Western Region, having been inherited by the Great Western Railway from the Weston, Clevedon and Portishead Railway. BR gave the locomotives the power classification 0P, indicating that the locomotives were primarily passenger locomotives, but were among the least powerful on the system. The locomotives remained employed much as they had been under Southern Railway ownership, with roles centred on working over the lightly laid and weight restricted branches. However, the class were becoming increasingly expensive to maintain through physical wear and increased age of components. The future of the class was thrown into doubt with the publication of the Modernisation Plan, which made provision to close many of the routes still operated by the class. The main two routes still retaining 'Terrier' operations were the Kent & East Sussex Railway and the Hayling Island branch. The former closed due to being unprofitable in 1961. The line to Hayling Island remained profitable, however, primarily due to the heavy traffic in summer. The condition of the bridge over Langstone Harbour was, however, deteriorating, and the Southern Region designated the bridge as being beyond economic repair. The final scheduled services over the line were run on 3 November 1963, and a special 'topped and tailed' by 32636 and 32670 the following day. The final scheduled train was notable for being one of the last steam hauled mixed trains. With the closure of this line, BR decided to