Thatcher turned the UK economy around, she did not, as widely believed, cut state spending in real terms. In increased on average throughout her period, but the difference is that the economy grew faster, and she shrank the size of the state through privatisation.
Inflation was tamed, a vast industrial sector that suffered from chronically poor productivity was restructured, and limits on innovation and competition were dramatically reduced. Air, telecommunications, bus, rail and energy monopolies were broken up, and entrepreneurship grew once again.
Thatcher took on the militant unions, the unions that hated secret ballots that they couldn't rig, the unions that forced workers to be members, the unions that had funding and support from the totalitarian USSR. She won, as these violent institutions (that bullied and harassed those who valued their jobs more than the unionists) were no longer in control of the economy.
She ejected the vile military dictatorship of Argentina from the Falklands, and with Ronald Reagan confronted the grand evil of the Soviet Union, until Mikhail Gorbachev demonstrated he was willing to let the shackles of Soviet imperialism be removed.
She resisted the growth of the European Community beyond being merely a collaboration of free trade and movement of people, to being an institution of subsidy and regulation. She saw the EC as reversing what she was trying to do in deregulating Britain. She has been proven right.
However, overall she turned the tide on a postwar consensus of socialist mediocrity, a view that individuals knew best how to live their lives (though sadly with a conservative streak that did not stretch to social liberalism), and that success and entrepreneurship would save Britain, not more state sector control and bureaucracy. Allowing people to buy their own state houses at a discount opened up home ownership to thousands, and started to wind back the desolate decaying depression of council house dominated Britain.
Despite much hatred of her by the left, she did not dismantle the welfare state, or the NHS or the state schooling system. All got more funding in real terms under Thatcher's rule, and all were too difficult to seriously confront and reform. She was not without faults, her big mistake was the Poll Tax, as people resisted paying more for local government - when they really needed local government to shrink further. Her warmth towards Pinochet of Chile was a tragic mistake too, her love of the free market and hatred of socialism blinded her to the brutality of his dictatorship. She was, after all, a conservative, not a libertarian.
So today Britain should celebrate what she did. She was so successful it transformed the Labour Party so that, to some extent, the Blair government continued her reforms and did little to roll back the clock (primarily it just spent more on what the government did). She did not defeat socialism in Britain, but she slashed it back - the spirit and philosophy of socialism still pumps through the veins of this country, and is seen in petty fascist local government, the continued growth in the state sector, and the stifling lack of accountability from the NHS behemoth.
Much of Britain still seethes with hatred for success and the wealthy, as can be seen by the majority support for the new 50% top income tax rate, but it at least has had a chance, and as a result of Maggie has not slipped back like Italy and France have over the past few decades. It is a country I enjoy living and working in because of this - and I hope Baroness Thatcher is aware of that anniversary, and can quietly enjoy it with loved ones.
I for one am glad at the revolution she brought, she had more courage and fortitude than any of the spineless little men she led, and the ones she needed to fight to get where she was. The Conservative Party sadly being a repositary of too many privileged mediocrities. I wish the Conservatives could have the courage to complete the job, and that the philosophical arguments for less government can be argued more forcefully. Perhaps one day, and perhaps Britain can start to be grateful for what she did.
UPDATE: The Sunday Times says "It's time to invoke the spirit of Maggie".
The Times reports on seven born at the time, only one who is wholly negative, some have shown the entrepreneurial spirit she helped unlock.
David Aaronvitch (typically centre left) in the Times writes how those in 1979 couldn't have anticipated what was to come, from the winter of discontent and the punk era to...
The Daily Telegraph has comments from friends and foes alike, but has a whole section on her (unsurprisingly)
The Daily Telegraph asks David Cameron to dare to be unpopular
"Mr Cameron will need a degree of commitment and courage at least as great as Margaret Thatcher’s, because if he is to have any chance of success, he will have to pursue policies which generate as much anger, bitterness and unpopularity as those of the “Iron Lady”. That, of course, should not stop him – any more than it stopped her"
Or if you want to see the slithering beast that she helped slay read the comments on the Guardian's pathetic little piece, where she is blamed for British kids being obese
but the leftwing Mirror is at least dignified.
Peter Hitchens in the Daily Mail laments how she failed, as Major and Labour afterwards did much damage.