The 1926 Electricity Act
In 1918 the 'Williamson Report' commissioned by the UK Government stated that the very diverse nature of electricity production (there were not less than 600 electrical power generators in the UK) resulted in the costs to the customer being much greater than would be the case if larger interconnected units were used. The Electricity (Supply) Act 1919 established the five member Electricity Commissioners as regulator. Opposition in the House of Lords meant the Electricity Commissioners had very little power, so very few improvements could be made.
In 1925, the Cabinet asked Lord Weir to review the position. The government pushed through the landmark Electricity (Supply) Act 1926, which gave the Electricity Commissioners the powers they needed and established the Central Electricity Board to build and operate the National Grid, and control but not own the power stations.
From 1926 until 1947 when the Electricity System was nationalised, the number of generating stations was reduced to 132; These were owned by a combination of private and municipal bodies. According to an article in the Times both the municipal and private producers of electricity "accepted their responsibilities in making the supply of electricity an instrument of social and national service".
It appears that the arrangements of the 1926 Act for creating a more effective electricity system worked well.