The South Eastern Railway (SER) O Class (some of which were later rebuilt, becoming the O1 Class) was a class of 0-6-0 steam locomotive designed for freight work, and were the main freight engines of the SER, and later the South Eastern and Chatham Railway (SECR) for a number of years. However, they were displaced by the more powerful C class locomotives following the amalgamation of the South Eastern Railway and London, Chatham and Dover Railway (LCDR) in 1899. This relegated the class to working on the numerous branch lines in Kent, on both passenger and freight work. They worked most notably on the Kent & East Sussex Railway and East Kent Railway, operating coal trains from the Kent coal fields to London, as well as shunting work at such locations as Shepherds Well, Hoo Junction and Ashford. The majority were withdrawn before the outbreak of the Second World War in 1939, and those that remained were slowly withdrawn from nationalisation onwards. The death knell for the final few members of the class came with the Modernisation Plan of 1955, which closed down many of the branch lines they continued to serve in Kent, which included the branch lines to locations such as Hawkhurst, New Romney, Tenterden and the Kent coal fields. Those lines which remained open generally either lost their freight services or were dieselised. All members of the class had been withdrawn by 1962, and only one member of the class has survived scrapping. Construction 122 locomotives of the O class were built between 1878 and 1899, the last five entering service after the SER locomotive stock had been pooled with that of the LCDR to form the SECR. Sharp, Stewart and Company received four orders totalling 65: The balance (57 locomotives) were built at Ashford Works between 1882 and 1899, their numbers being scattered between 1 and 258, plus 299–301, 314–8, 331–4. Rebuilding 28 of the O class locomotives were given replacement boilers between 1900 and 1923, of basically similar dimensions to the originals; however, the fireboxes were deeper, and so the boiler was mounted higher in the frames. Between 1903 and 1932, 59 locomotives were given larger boilers, of the same type as was fitted to the SECR H class 0-4-4T; these rebuilds were designated the O1 class. Withdrawal Preservation One O1 class, SECR No. 65 (SR Nos. A65 and 1065, BR No. 31065) has been