tower" was erected near Edinburgh on 14 July 1928, and work was completed in September 1933, ahead of schedule and on budget. It began operating in 1933 as a series of regional grids with auxiliary interconnections for emergency use. Following the unauthorised but successful short term parallelling of all regional grids by the night-time engineers on 29 October 1937, by 1938 the grid was operating as a national system. The growth by then in the number of electricity users was the fastest in the world, rising from three quarters of a million in 1920 to nine million in 1938. The grid proved its worth during the Blitz, when South Wales provided power to replace lost output from Battersea and Fulham power stations. The grid was nationalised by the Electricity Act 1947, which also created the British Electricity Authority. In 1949, the British Electricity Authority decided to upgrade the grid by adding 275 kV links. At its inception in 1950, the 275 kV Transmission System was designed to form part of a national supply system with an anticipated total demand of 30,000 MW by 1970. The predicted demand was already exceeded by 1960. This rapid growth led the Central Electricity Generating Board (created in 1958) to carry out a study in 1960 of future transmission needs. Considered in the study, together with the increased demand, was the effect on the transmission system of the rapid advances in generator design resulting in projected power stations of 2,000–3,000 MW installed capacity. These new stations were mostly to be sited where advantage could be taken of a surplus of cheap low-grade fuel and adequate supplies of cooling water, but these sites did not coincide with the load centres. West Burton's 4 × 500 MW machines, in the Nottinghamshire coalfield near the River Trent, is an example. These developments shifted the emphasis on the transmission system from interconnection to bulk power transfers from the generation areas to the load centres, such as the anticipated transfer in 1970 of some 6,000 MW from the Midlands to the home counties. Continued reinforcement and extension of the 275 kV systems was examined as a possible solution. However, in addition to the technical problem of high fault levels, many more lines would have been required to obtain the estimated transfers at 275 kV. As this was not consistent with the Central Electricity Generating Board's policy of preservation of amenities,