It was apparent long before then but since 2008 and the banking collapse its been obvious to any fool who chose to look that we live in a rather peculiar "state capitalist" system in which government is there to buffer the knocks but never to receive any of those Capitalist benefits: like keeping the profits. It's effectively the only real economic difference in practice between state capitalism in China and here where under the dogmas of "small government" (excluding magic bailouts and military spending which both apparently need big government to provide big money) & "private means efficient" anything state owned that made money had been rapidly privatised under Tory and Labour: often given away at absurd prices which bore no relation to their genuine worth. Some (like Railtrack) were picked up again later alongside the bill by the state once the private owners had cleaned it out of cash and assets.
In effect "Nationalisation" is merely a means of handing someone else: ie: the public, the bill or reconstruction costs once the asset or utility has been screwed into the ground or financially abused. Once billions have been spent by the government to maintain or refinance the hapless "asset" it's fate is to be privatised at a loss yet again to cheers of "...trebles all around!" in the city. Effectively "nationalisation" under our system is a vehicle whose only allowable function is to provide free long term money for private businesses.