The MSP is not expected to attend this year's party conference in Inverness.

Earlier this year she was deselected as an SNP candidate in all but name as a result of her refusal to toe the party line since entering the Holyrood parliament three years ago as a list MSP for the Lothians.

Margo MacDonald: Turbulent career

In the run-up to the Inverness conference Ms MacDonald told BBC News Online she believed the party had lost its radical edge with the effect of dropping a significant hint about her future plans.

She said: "I don't think the SNP is as radical. I've been urged to stand by an amazing spectrum of people who actually have the same sort of criticisms of the political process that I have.

"A great number of people believe this Scottish Parliament needs independent members."

Ms MacDonald's place in the history of the SNP was assured by her win in a 1973 Westminster by-election for the Glasgow Govan seat.

The forces of darkness that lurk around the corridors of power in the second floor of the parliament headquarters have been saying a number of things about me recently, not all of which have been completely true

Margo MacDonald MSP

But since becoming an MSP her political path has been less clear as a result of a series of disagreements with the party's hierarchy.

She remains a party member, but the high profile row over her deselection prompted five of the seven office bearers in the Edinburgh South constituency association to resign.

Prior to that Ms MacDonald confirmed she had a mild form of Parkinson's Disease, after condemning the "dark forces" in the party she believed had given the information to the media to undermine her.

When she said she would not stand for the SNP in 2003 following her relegation former party leader Alex Salmond launched a stinging attack.

On the hustings in Edinburgh

He said she had a long and turbulent history with the party and she could no longer count on its generosity.

Ms MacDonald fell out with current leader John Swinney over far-right French politician Jean-Marie Le Pen, when he wrote to her to express his disagreement with comments she made regarding Mr Le Pen.

Lost the plot

In a newspaper article, Ms MacDonald said the French National Front leader was "intellectually robust" while his "logic was difficult to fault".

Responding to her leader's letter and the newspaper article, Ms MacDonald said she was not a racist but was merely attempting to analyse the French presidential elections.

She attracted the attention of Holyrood presiding officer Sir David Steel when she joined a protest against nuclear weapons which disrupted the business in the main chamber.

In June 2000 she received a written warning from party chiefs for what was described as a "severe breach of discipline".

Unexploded ordnance

Party whips said she had missed a parliamentary vote without permission and had briefed a Sunday newspaper against party policy.

And in 1999 she warned the party to forget about buzzwords like modernisation and focus on the real issue - Scottish independence.

Her strong statement came during a BBC Radio 4 interview in which she said some nationalists had "lost the plot".

As well as her disagreements with and criticisms of the party leadership, Ms MacDonald has ensured herself a consistently high media profile by her outspoken views on a number of issues at Holyrood.

Ms MacDonald: outspoken at Holyrood

She has been a stern critic of the new parliament building project, has championed the rights of prostitutes and has also been central to the debate about MSPs' pay.

The former journalist has also raised the issue of cannabis in the Scottish Parliament, trying to garner support for a full debate.

The SNP used to call her the blonde bombshell, but while the party debates at Inverness, Margo MacDonald is unexploded ordnance, waiting to go off.