IMHO it is all a conspiracy- Initially after WW2 with Labour all energy was Nationalized -it was probably needed because individual producers/suppliers[the one and the same] were in a chaotic state.
But it stifled investment and did not stop strikes.
So privatization was the word - get the mess of the Governments back.
But it was not really privatization.
The big organizations from overseas bought in- in both the the generator and supplier sectors- so in name they were separate in reality were the same, as in a 'group' business- A group business is where a coven [or group] of enterprises of a similar nature trade with each other- each taking profit[raising the end price] before the items/products get to the real customer.
In this case the 'producers/generators'actually sell 'wholesale' to the distribution network - National Grid' who sell to the distributors [same
firms]so that the name of the firm at the top of your Electricity/Gas bill is really a 'shell company' that er writes bills - that's all it does.[for a profit of course]
National Grid is, by the way busy at the same, in the USA too.