The methods used by Thatcher were legal in that they went through parliament - some of the restrictions anyway. In other words they had to pass laws to make them legal. You can make anything legal by putting stuff through your legislature.
The cost of bringing coal out has been subsidised around the world for many, many decades in most nations during that time since it was seen as a critical strategic industry - remember what happened to Russia when their miners went out in support of Yeltsin?
The problem is that such industrial power then carries with it a great deal of responsibility and the fact is that were had pretty much run into a situation where the UK miners were deciding which governments they approved of, and which they didn’t - it is not difficult to imagine how this was seen in many quarters as a threat to our democracy. Arthur Scargill was seen as the unacceptable face of that power.
In order to destroy this power there were legal means, but I wonder if warrantless wire tapping was legal, or the many subsequent arrests that followed during various gatherings, where appeals overturned many convictions.
We also had extremely serious media manipulations over events at these gatherings, the most notable one was at Orgreave coke works where BBC reports showed footage of miners attacking the police without provocation - of course that footage had been edited - the miners actually ran from the police who had charged them with horses and a body of officers. Those miners ran off until they came to a dry stone wall, which was then picked up and thrown at the police in an attempt to defend themselves. The police retreated before charging again. BBC did make an unreserved apology for the editing many years later. You can multiply that propaganda by several thousand times by the rest of the media throughout the miners strike and in every national industrial dispute since then.
Personally I saw miners wives attacked by police with batons, despite there being no emergency that warranted such an assault, and make no mistake, assault it was.
There were countless such incidents, police officers removing their epaulette numbers so they could not be held to account. I also know, personally a number of former soldiers who were dressed up as police officers - (don’t ask me to name them I won’t) I wonder how the prospect martial law would have gone down with the public?
I regret that some of this might seem like tin-foil hat CT material, I also can understand why it was all done.
Thing is, you still must remember that it was seen as a defence of our national democracy, and in such a circumstance the means used to achieve it were unimportant to those in administration.
The result is that this was seen as a keystone of trade union power, by pulling it away the whole façade of union muscle was seriously damaged, and this was followed up by anti trade union legislation - the unions have been hobbled, for good or bad. This is probably the main long term legacy of that industrial dispute.
In the shorter term, we are no paying to import subsidised coal from other countries -it isn’t saving us any money. Coal was integrated into whole system of rail, electricity generation, steel making etc. and these industries were sited in proximity to improve logistics. The removal of a major part of that has been extremely damaging to those other industries - all are either costing us a lot more, or have declined drastically - you might argue that the whole set up of state control was no longer viable anyway.
Part of the destruction of the unions was to break up these formerly state controlled industries and sell them off in much smaller pieces. We now have far fewer people working in any of those industries, railways receive greater state support under private ownership than they did under the national BR board,
The energy companies have partly reintegrated themselves in such a way that there are 6 big players who generate, transmit and distribute power - however their system of inter-charging different arms of the same organisation based upon their function means that they have an effective monopoly whose accounts are incredibly difficult to work out, suspicions are that the combined profits for those companies is not the 5% they claim, but across the industry as a whole its upwards of25%. There is more than a little suspicion that this industry is operating as a cartel (I have been deliberately conservative on that figure - mush higher ones are in circulation)
So we a paying more for everything, and the owners are usually foreign multinationals.
Socially the effects in the various mining communities have been mostly disastrous, think of any one-industry town where the company closes down and you can imagine - crime has climbed dramatically and whole regions are blighted with unemployment. It has also made the divide between the South East of the country and everywhere else much greater.
It is pretty much the London-centric polices of successive administrations that have led to calls for independence by Scotland and Wales - to such an extent that Scotland is going to have a vote whether to leave the Union - in short, Thatcher - that great national patriot - has actually done more to break up the United Kingdom than the Spanish, French or the Germans - I hope her supporters understand that.
The reduction of the emission of greenhouse gases was and continues to be a smokescreen, physically and metaphorically, it just simply would not do to admit that somehow a better outcome might have been achieved, and no Conservative politician will admit the truth, that the miner strike was pretty much a war against one section of the workforce - which it was, and probably was necessary too.
Folks who live in the South East pretty much cannot see what really happened, or don’t want to admit to themselves the reality of those unpleasant means to achieve a certain end.