You've described the CEGB that we used to have, the Central Electricity Generating Board.
We also had one rail company, one telephone company, one gas company and Metropolitan Water Boards. all British owned and at lower costs to us. We are supposed to have one health company, the NHS, but even that has been sold off in parts, like all the local doctors surgery practices sold off to US companies making big money from them.
Now most of this is foreign owned by investors for profit. The Tory holocaust.
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This might be eventually one of the very few Brexit bonuses. !. Under EU guidance in the 90s we were encouraged to break up state monopolies . Whether it was actually a requirement or a request ,I never recalled, but certainly the mantra was .. Competition makes for better public services. It doesn't!!!!. .
The privatisation of the phone system was particularly obnoxious.
Our Electricity service did succeed in retaining most of its integrity. The ESB was split into two entities EirGrid, which manages and build the Network and infrastructure, and Electric Ireland who can own generators and sells power to customers . Every 15 minutes the generators bid to supply power for the next 15 minutes The innovation is that other suppliers can also own generators and sell power. So every year we the consumers need to change supplier in order to get bonuses.. So I am finally, having gone round the houses, back with Electric Ireland ...whom I never really wanted to leave.
Water is where the Irish public finally blew their tops .. and is the reason why SF have as much support as they do. It used to be a county council competence but the more conservative wing of FG wanted it a Private Property... . Anyway it is very strongly State enterprise, and there is talk of making it a Constitutional Right , that it cannot be sold.