[SideValve]

Like most of the previously publicly owned companies they were nationalised because the government of the day considered it essential to control an industry of national importance. It didn't used to be split on party lines, it used to be based solely on perceived need, whether it be for national security or social need. Some were natural monopolies able to make large profits, some were important to the country but financially were never viable in private ownership. Some made little logical sense to keep in public ownership over the long term, some made perfect sense.

They usually paid employees lower than average pay but gave better all round terms including pensions.

Whatever has been in manifestos we have gone further than many other countries in divesting ourselves of publicly controlled companies.

I know how much things have changed over my lifetime and the younger guys I work with cant believe how much used to be publicly owned.
The change in policy has been in place for about 40 years now. I guess only future historians will really be able to judge whether it was a good idea or not.
Personally (and this is an economic point rather than a political one) I was taught in 6th form about the "multiplier effect" how when a govt put money into the system it went round and round and multiplied. Seems to me that if so many of our companies are owned outside the UK then on each trip round that effect largely goes to others benefit. Also many of the businesses work in markets where competition just isnt effective. Finally (and this is a more social point) arguably it contributes to our feeling of loss of prestige & control.
Problem is, no matter the long term benefit of bringing them back into public ownership, its likely to be naffing expensive - certainly costing more than we got when they were flogged off. Guess its one of those things - can we afford to vs can we afford not to.