I remember Margo MacDonald hitting the headlines as SNP candidate in the Govan by-election of 1973.

Despite my personal admiration of her, I was campaigning against her because of my loyalty to the Labour Party. The Labour candidate was a likeable wee man, a local barber by the name of Harry Selby. In the heat of a by-election, where personalities as well as policies come under intense scrutiny, Harry was no match for Margo. Labour's campaign was an absolute shambles. I remember being sent out to canvass with a list of addresses that did not even exist because the houses had long since been demolished. Parts of Govan at that time resembled a blitzed warzone and many of the people saw Margo as their saviour. She won a famous victory in that by-election but, a few months later, she was defeated at the General Election.

In 1978, Margo popped up again as SNP candidate in a Hamilton by-election. Margo, who was Lanarkshire born and bred, boldly accused the Labour candidate, George Robertson, who had no local roots, of simply using Hamilton as a stepping stone to Westminster to further his own political career. During the campaign, she described George as the invisible man, who spent most of his time hiding in his campaign office because he was afraid to confront her. Eventually there was a big debate held in front of a packed audience in Hamilton Town Hall, when many neutral observers felt that Margo wiped the floor with George. Nevertheless, Labour won the by-election, largely due to the momentum following Donald Dewar's stunning victory against the SNP in the Garscadden by-election a few weeks earlier. If Hamilton had preceded Garscadden, Margo might have beaten George Robertson and changed the course of history.

Although she was never re-elected to Westminster, Margo remained very pro-active in the campaign for a Scottish parliament. Following the 1979 General Election, Margaret Thatcher repealed the Scotland Act. There were many politicians of various parties who wanted to bury the entire home-rule project but people like Margo kept the flag flying through difficult times. I remember us both attending the launch of the cross-party Campaign for a Scottish Assembly in 1980. She reprimanded me for attacking the Thatcher Government because she wanted to woo the Scottish Tories and include them in an all-party campaign. I took the view that was a lost cause but who was I to argue with Margo?

Our paths crossed again when we were both elected to the Scottish Parliament in 1999. At the start of that first parliament, I found myself ploughing a lone furrow. I was the only independent MSP to be elected in 1999 but I soon found in Margo a kindred spirit. At that time, she was still a member of the SNP, although her independence of mind must have caused nightmares for the party bosses who preferred control freakery to any originality of thought or expression.

Most of the MSPs at that time had no previous parliamentary experience and they simply toed the party line on every issue. But not Margo. She was scathing in her attacks on the escalating cost of the new parliament building and she was not afraid to criticise her own party on other matters. Perhaps that was her undoing in terms of her party candidature. Like me, she discovered that, in politics, your deadliest enemies are sometimes in your own party. There were allegations of skulduggery and, in the event, Margo was demoted in the SNP list for Lothian, making it very difficult for her to be re-elected as an SNP member, if not impossible. She then took the courageous decision to stand as an independent candidate in the 2003 elections to the Scottish Parliament.

She asked for my advice before announcing her decision to take that route and she and her husband, Jim Sillars, came to my house for a confab. Throughout that Sunday afternoon, she spent a lot of the time holding my baby son, Adam, in her arms, and blethering away about everything under the sun. But underneath I could sense her steely determination not to give in and to take her case all the way to the court of public opinion, where the jury would be the electorate of Lothian. That would, of course, mean expulsion from the SNP.

I gave Margo a few tips from my experience as an independent candidate but Margo did not really need any advice from me. She was a natural, and she romped home as an independent in three successive elections.

The last time I shared a platform with her was at the Independence Rally on Calton Hill last September. It was a monumental task helping her up on to the platform but, when she eventually managed, she gave another virtuoso performance to rapturous applause. She was fond of telling such audiences that, in order to win the referendum, all that was required was for each supporter of independence to convert one person to the cause.

I sometimes hear people speculating about who would do a good job as an elected head of state in an independent Scotland. If Margo were to stand, she would have won hands down. She was a lass o' pairts, a woman of independent mind and a bonnie fechter.