She was just 30 when she burst onto the political scene in 1973 as the winner of a famous by-election in Glasgow Govan. A strikingly attractive former physical education teacher, the newspapers immediately dubbed her the "blonde bombshell".
Margo MacDonald, 70, died Friday. She was a passionate speaker with fiery left-wing politics and a charismatic personality, even bigger than her famous platinum hair.
Her victory for the Scottish National Party (SNP) over Labour in Govan, a working class shipbuilding district on the south side of the River Clyde, electrified Scottish politics. With the exception of a narrow Conservative win in 1950, Labour had held the seat continuously since 1918.
According to former Labour MP Tam Dalyell, Macdonald's success in Govan marked the beginning of Labour leader Harold Wilson's conversion to Scottish devolution. This was the start of a journey that could end in September with a "yes" vote in the referendum on independence.
MacDonald lost out by 543 votes in the general election three months later, but she had helped to generate an SNP surge that caused panic among the major parties. With her as deputy leader, the SNP went on to win 11 seats in what is still its greatest ever Westminster success.
For the time the Nationalists seemed unstoppable. She had youth and glamour and a successful campaign slogan: "It's Scotland's Oil." But it wasn't enough. The decade ended in bitter disappointment for MacDonald and the SNP.
Move to journalism
In 1979, the party's hopes for Scottish self-government were defeated in a referendum, despite a majority of those who took part actually voting "yes". A few weeks later, Margaret Thatcher was elected prime minister.
MacDonald forged a new career as a journalist and presenter with Scottish Television. Her greatest strength was her ability to connect with people - she helped set up Scotland's first telephone help lines for drug addicts and AIDS sufferers.
Her political comeback had to wait until 1999 when the Scottish Parliament finally came into being. She never held ministerial office or sat on the front bench, but she won a reputation as Scotland's greatest parliamentarian.
MacDonald still had that ability to speak to anyone. Former Labour MSP John Park recalls a reception in Holyrood Palace when she shouted over to Prince Philip, "Haw Philip come here and meet John, he's new."
However, what really marked her out was her willingness to ask tough questions. She interrogated the spiralling cost of the Holyrood building project with forensic scrutiny, and eventually won an independent inquiry from the government.
Under John Swinney's leadership, the SNP had become a party of grey men in grey kilts. MacDonald was too much for them to handle and she was expelled in 2003 after announcing she would stand as an independent.
She romped home in the subsequent election and gained a new lease on life as a popular politician willing to take on unpopular issues.
Prostitution was one of her causes. She irked Edinburgh's culturally Presbyterian establishment by arguing for tolerance zones, which she believed would offer sex workers greater safety.
Her final campaign was deeply personal. She wanted to change the law so that she had the right to decide how and when her life would end.
I now know people who have certain degenerative conditions and the possibility of a very disturbing, very unhappy and, from their point of view, very undignified end. They know that is lying in front of them. My real motivation is knowing the people that this will help.
Battle with Parkinson's
MacDonald loved American country music and once said she had been "mad for the dancing". But for the past 12 years she struggled bravely with Parkinson's disease, a degenerative condition that made her shake and slowed her movements.
She struggled to walk without sticks and used what she called a "Margo mobile" to get around the Scottish Parliament, joking it was great for clearing people out the way.
Her bill, which is now being taken forward by the Green Party, would enable anyone in Scotland over 16 years of age with a terminal illness, whose life has become intolerable, to seek help to commit suicide. It is a controversial piece of legislation that has attracted strong opposition from religious groups and the medical profession.
When asked about this issue in 2012, MacDonald had to fight back tears when she spoke about the experiences of some of the people who were supporting her.
"I now know people who have certain degenerative conditions and the possibility of a very disturbing, very unhappy and, from their point of view, very undignified end. They know that is lying in front of them. My real motivation is knowing the people that this will help."
MacDonald's husband, Jim Sillars, also a former SNP deputy leader, said her death had robbed Scotland "of one of its greatest talents" and the "brightest light" in the Scottish political scene had gone out.
Her greatest cause was Scottish independence, but MacDonald didn't live long enough to take part in the September 18 referendum.
Follow Andrew McFadyen on Twitter: @apmcfadyen