The route was started on 24 June 1961 as Route 26, when Route Twisk, originally a military road, was opened to the public. Originally KMB operated it as a test route only, but because of the positive response received, the route became a permanent route. Due to the steepness of Route Twisk, the route was served using Albions for a long period of time. At that time, the route ran between Jordan Road Ferry Pier and Yuen Long, and was initially an express route, having only two stops between Lai Chi Kok and Shek Kong, which were at Tsuen Wan Town Centre and Tai Mo Shan. On 16 July 1973, as part of KMB's bus service arrangement scheme, the route was renumbered 51, and service was cut back to Tai Kok Tsui Ferry Pier.