She appeared as if from nowhere - no flashing lights, no sirens - accompanied by her moustachioed private detective, his meerkat eyes scanning the crowd for assassins. I stood there, with my straggly hair, in a long-sleeved Fred Perry shirt and a Muttley badge (as in Dastardly and Muttley). And the most powerful woman in the world made a beeline for me.

"The problem round here is the Tube stations," was her curious opener. "They're all equidistant and they're all a long walk away." She was quite right - or, rather, her special adviser, who must have briefed her, was quite right. There are three Tube stations, all about 20 minutes away. But however odd the small talk, there was nothing scary about her. She was just too familiar. From the age of seven until I was 19 - my politically sentient life from birth to adulthood - she was prime minister. I had met her twice as an 11-year-old when my father worked for her. Even now, it is hard not to think of her as an ever-present part of British life, like the Queen or the weather.

Nineteen years on, I remain an admirer, for the reasons all her admirers give. She got the economy going, expanded home ownership, cut tax, took on the unions, defended the Falklands, kept European integration in check, obliterated sexist barriers to power, made Britain more meritocratic and less class-conscious, and generally did the necessary but unpopular.

But - and I don't blame this "but" on her, rather on the after-effects of her successful econ­omic policy - the wealth produced by her reforms led to a worship of money as well as dissatisfaction from those who didn't benefit.

At college I refused to burn my poll tax form in a brazier. It didn’t go down well

She remains powerfully divisive. When a theatre producer decapitated her statue in the Guildhall Art Gallery with a cricket bat in 2002, it was a sort of compliment - who would attack a statue of John Major 12 years after he left power?

She was hated - real, deep hate - when I was at university, too. That summer, in 1990, I refused to burn my poll tax form in a brazier in the cloisters of Magdalen College, Oxford. It didn't go down well. On St Valentine's Day, I received a mocking card that read: "True Blue, Baby, I Love You." Teaching in Prague that August, I shared a flat with an otherwise affable Welshman who swore viciously at me when I praised her. Hatred of Mrs T was a badge of political honour for my contemporaries, but they jumped on her City bandwagon quickly enough, laying aside their protest flags, cutting their hair and putting on charcoal grey suits for their bank interviews. They hated her, but they knew she was right.

Mrs Thatcher was no Gordon Gecko. Her man­tra wasn't that greed is good; she understood that greed is inevitable in man, and students, too. Under Thatcher, that greed was harnessed to produce greater returns for more people and, after Big Bang in 1986, enormous City fortunes were made. What would her enemies have preferred: the old system, with jobs for the boys, over-regulation and antiquated, open-outcry deals?

Another by-product of this money obsession has been an epidemic of sadness. Tremendous expectations have been raised by consumer choice and the me-first cult. The inability to keep up has led to a boom in antidepressants, sleeping pills and anti-anxiety drugs, of visits to psychiatrists and therapists. Open the mirrored cabinets in half my friends' bathrooms, and you'll find pack up on pack of Xanax and Prozac.

You can hardly say this is Mrs Thatcher's fault. Her one drug was malt whisky, and even that wasn't applied as liberally as is suggested in Margaret, BBC2's rather affectionate drama about her, broadcast on 26 February.

But you can say, in a Britain that worked again, where some earned fortunes and most improved their standard of living, where hard work was rewarded - all good - that expectations of material success were raised. And those who failed to reach them, as well as some who did, reached instead for that mirrored cabinet over the sink.

Harry Mount's "A Lust for Window Sills: a Lover's Guide to British Buildings from Portcullis to Pebble-Dash” is published by Little, Brown (£12.99)