As in so many other areas, the public perception of what Margaret Thatcher was like to work with was dictated by the long-running ITV series Spitting Image.

Asked how she'd like her steak by a waitress, the Prime Minister replies: "Oh, raw please." "And what about the vegetables?" adds the waitress. "Oh," coos Mrs Thatcher, "they'll [the Cabinet] have the same as me."

But this depiction of the UK's first female premier as dictatorial, domineering and contemptuous of those who served her was a caricature.

Although it contained a grain of truth – as good satire always does – she was inclined to be robustly pragmatic. Mrs Thatcher loved an argument and, as long as Cabinet colleagues gave as good as they got, they stood a chance of getting their own way.

George Younger, her Scottish Secretary from 1979-86, was a case in point. "She is not a very good chairman of Cabinet as she talks too much herself, and never lets an argument develop without her steering it all the time," he recorded in his diary in 1979. "But she doesn't bear grudges and, after hammering at you for an hour in a very aggressive way, she can see your point of view and even change her own."

Mr Younger, of course, knew how to "play" the prime minister, although this was subject to the law of diminishing returns. While Gentleman George managed to win reprieves for Ravenscraig and escape sizeable cuts afflicting other government departments, his successor Malcolm Rifkind found it altogether more difficult. While Mrs Thatcher trusted Mr Younger, who knew his place, Rifkind was ambitious and therefore regarded with suspicion.

In fact, Mrs Thatcher's tendency to defer to advice, in one disastrous case from Mr Younger and Willie Whitelaw, was to prove her undoing. Confronted by a disastrous Scottish rates revaluation in 1985, her instinct was to gradually phase in the community charge, or "poll tax", across the UK. Willie and George said no, Scotland must be allowed to go first. The rest, as they say, is history.

Although Mrs Thatcher certainly had a temper, I cannot think of a single recorded incident in which she was rude to an underling, indeed quite the contrary. Political colleagues were, of course, a different matter (particularly poor old Geoffrey Howe) but, considering contemporary reports, about the projectile anger of Gordon Brown, or the scathing criticism doled out by Alex Salmond, Mrs Thatcher emerges pretty well in terms of basic humanity.

She also responded well to ideas, rarely having had any of her own. When Bill Hughes, the then chairman of the Scottish CBI, came up with the idea for something called "Enterprise Scotland" (basically merging Scotland's training and development agencies), he found himself discussing it with the prime minister at Chequers and Downing Street within days. She made just one change, reversing Hughes's proposed name so it became "Scottish Enterprise".

"Mrs Thatcher could take decisions. She didn't mess about," Mr Hughes recalled later. "She saw Scottish Enterprise as a solution - what she wasn't going to do was compromise her Thatcherism." Remarkably, the so-called "Hughes initiative" went from an idea on a sheet of A4 to an Act of Parliament within a year.

As well as being decisive, no contemporary account contradicts the fact Mrs Thatcher worked incredibly hard. A cursory glance at her formidable archive reveals every document was digested and commented upon, while speeches – including the famous "Sermon on the Mound" – were worked and reworked. When reminded his successor as Tory leader needed only four hours' sleep a night, Sir Edward Heath drawled: "Yes, one saw the consequences."

l David Torrance is the author of We in Scotland – Thatcherism in a Cold Climate (Birlinn 2009)