Over the last 20 years, we have had two British political parties in office, so do I take what you say as a joint condemnation of both their policies regarding the cost of energy to large industrial users over that 20 year time period.
Except it's not quite as simple as that. We've had two political parties, yes - but under the Conservative's watch until 1997, things were under control. We had sufficient capacity, and the early ideas were there for replacements as needed at the appropriate time. There's not much they could have done to accelerate the building of new units, as they'd have simply come online too early (leading to overcapacity problems, with similar results to the current steel crisis).
The problem is that since 1997, the UK has signed up to an number of climate change agreements, mandating the closure of the big (polluting) coal stations that formed the main backbone of the UK power network. That wouldn't (shouldn't) have been a problem as logically you'd just bring all the plans forward a few years.
Except Labour didn't. They just buried their heads in the sand and assumed that you could throw together a gas fired station in a year or two, and a nuclear station in 5 or so.
At least with the Tories back at the helm things are starting to get back on track (just with the added hurdles of the quirks of privatisation and undercapacity to overcome). I think that once Hinkley Point C starts construction, a lot of other projects will then leap into the build stage within a year or two.
The main problem has always been the money aspect - nuclear stations are horrifically expensive to build & run, so there needs to be an assurance that they will at least cover their costs. I know there's a lot of anger that the subsidies for renewals have been cut back, but the fact is that wind power will never generate enough power to supply the country, and solar needs a lot more research before it becomes viable. We need to be sensible with what the money is used on.
Anyway - wildly off topic for a thread about Teesside seel.
(As a footnote, Tata Speciality at Rotherham doesn't appear to be shedding any jobs. If there is a future for UK Steel, maybe the speciality/technical/engineering steel is the answer?)