Politics is very simple; and great politicians (the epithet 'great' meaning that they did something constructive to turn a tide, as contrasted with most politicians who do nothing and/or make matters worse) - such as Margaret Thatcher - typically do one positive thing.
(Making one large and complex thing is enough for greatness - one achievement is infinitely more than none! Construction is vastly more difficult than destruction. Creation is much rarer than scavenging and parasitism.)
Then positive thing Mrs Thatcher did was to reverse decades of British economic decline.
This decline would almost-certainly have led Britain into an Argentinian-style (no irony intended) mega-economic collapse (about a century ago Argentina was - I understand - one of wealthiest of countries per capita). I have read economic and social analysts writing in the middle to late 1970s, and this fate was regarded as all-but inevitable for the UK.
Yet it did not happen. Margaret Thatcher diagnosed the problems, publicly repented of the policies of the past, told Britain what it needed to do ('roll back' socialism), explained that short term prosperity had to be sacrificed to the longer term, took the necessary measures and -
Sure enough, things did get worse, there was a period of sharp recession and exacerbated decline.
But Mrs Thatcher held the line until the battle was won, and the impending economic collapse was not just averted but reversed.
Then Britain had a period of strong economic growth.
Many economists had diagnosed Britain's problems; several politicians knew what needed to be done; perhaps several of these politicians could believe that these things could be done and might even have started the job of fixing the economy...
But only Mrs Thatcher could see-it-through in the face of a level of orchestrated vilification and misrepresentation from the Leftist intelligentsia and organized labour (and most of her own party) which was astonishing at the time and in retrospect.
(A process with which I, to my shame, participated to the max - I was on the wrong side in the Great War.)
The British economic turn-around was partial, temporary, and has long since been dissipated by her successors: but that is what Margaret Thatcher did, and we have lived-off-it (and, sadly, the borrowing and inflation made possible by expectation of its continuance) ever since the early 1980s.
It is very hard to think of other examples of this kind of reversal of decades of economic decline in such a large, complex and aged society as 1970s Britain - I think this must count as a world historic achievement.
Mrs Thatcher probably also did some other positive things; but else nothing she did was so clear-cut nor so objectively verifiable as the economic re-birth of Britian.
There is an important lesson which Leftist intellectuals ought to draw from this.
They were wrong about Mrs Thatcher.
At the time they (we) all totally believed they were right; we were filled with boundless moralizing zeal concerning our rightness - but the facts state otherwise.
The first lesson is that the Left intellectuals were wrong about Mrs Thatcher en masse and objectively and this ought to have led to a major reappraisal of the Left's understandings of the world and their modes of evaluation.
The second lesson is that the Left has utterly failed to make this honest appraisal of events, but instead denies the facts.
The third lesson is that the Left is therefore, now, profoundly dishonest, rotten, corrupted - and unteachable. Immune to experience. Utterly deficient in common sense.
Once the Left had succeeded in denying to itself the blatantly obvious economic 'miracle' wrought by Mrs Thatcher, and thus failed to acknowledge their major error; then a path was cleared for the Left to deny anything else inconvenient, and to construct public discourse via the mass media and the bureaucracy in order to endorse Leftist 'reality'.
So, the British attitude to Margaret Thatcher and her achievement was a road fork for national politics - as a country we made the wrong choice and took the false path of denial (especially in Scotland, Wales and the North of England); we have refused to learn the lessons taught by Mrs Thatcher - and inevitably we are reaping the consequences.