The local boards remained in existence until 1894, when they were both converted into Urban District Councils. In 1900 the Swindon New Town and Old Swindon urban districts were merged, to form a single municipal borough of Swindon. On 1 April 1974, the Local Government Act 1972 created a non-metropolitan district of Thamesdown, consisting of Swindon along with the former Highworth Rural District. The name alludes to the two natural boundaries of the region, the River Thames to the north and the Wiltshire and Marlborough Downs to the south. The name itself was described as "absurd and universally unpopular".