• Steven Purcell underwent treatment at a hospital specialising in drug and alcohol problems
The Scotsman can reveal that in a draft proposal from Mr Purcell's in-house team of advisers, he would have laid out the reasons for his sudden departure as the head of Scotland's largest local authority.
Yesterday, it was confirmed Mr Purcell had attended the Castle Craig clinic in the Borders for treatment. It specialises in the treatment of drug and drink addiction.
Under the plan discussed by Mr Purcell's aides over the past few fraught days, he would have made it clear he required treatment. The words "chemical dependency" were suggested as the term to be used to explain his condition.
However, Mr Purcell, 37, then brought in his own public relations advisers and, through them, drafted an alternative statement that blamed "stress and exhaustion" for his decision to quit.
The statement also cited the "strain of running one of the UK's largest authorities, combined with the added pressures of the Commonwealth Games planning and the controversy over Strathclyde Partnership for Transport".
Mr Purcell has told friends in the past 24 hours that he is "on the mend" after leaving Castle Craig some time on Tuesday. He is now understood to be in Glasgow, where he will continue his rehabilitation with his family. But the mysterious circumstances surrounding his departure have served only to heighten speculation about what prompted his decision.
His last political engagement was at a Labour fundraiser attended by Prime Minister Gordon Brown in Glasgow's Hilton Hotel last Thursday. Within hours, he had told aides of his desire to quit.
The Labour councillor is said to be hopeful of a return to politics, but close friends fear that the largely unexplained crisis that led to his departure from the top job in Glasgow will leave a question mark hanging over his future career.
In a further development, it emerged yesterday that the council had been warned prior to the leader's resignation that it could face a possible interdict from Mr Purcell's lawyers if it were to say anything about his health.
As a result, council officials were unable to answer questions about his whereabouts at the clinic.
Asked about the plan to refer to Mr Purcell's health problems in a statement, a spokesman for the council refused to comment last night.
Mr Purcell is now being represented by Jack Irvine, the head of PR agency Media House. Mr Irvine confirmed yesterday that his client had been admitted to the Castle Craig clinic, near Peebles, earlier this week.
In a statement, he said: "Councillor Steven Purcell is no longer a patient in Castle Craig Hospital. Councillor Purcell is recuperating with family and he asks the media to allow him time and space to recover to full health."
Mr Irvine would not say what treatment Mr Purcell had received. "Health is a private matter," he said. He also declined to comment on whether the former council boss had been admitted to the clinic by the NHS or as a private patient.
Some friends believe Mr Purcell should still be in hospital receiving treatment for his continuing health problems.
His departure from the council leader's post on Monday sent shockwaves through the Scottish Labour Party. Mr Purcell, who had made his name by securing the Commonwealth Games for his city, was widely seen as a potential future leader of the party north of the Border.
He had led the council in Glasgow for five years, during which time he pushed through a reforming agenda, winning him accolades from former prime minister Tony Blair. In 2006, he left his wife and came out as gay.
Yesterday, senior Labour figures tried to downplay the significance of his departure, with sources close to Scottish leader Iain Gray insistent that the party was still on track ahead of the forthcoming general election.
Mr Purcell's resignation was confirmed on Tuesday after news leaked out late on Monday night. That followed news of his departure being broken to council staff.
Labour MSPs said they had not picked up any signs that Mr Purcell was on the verge of quitting when they met him during talks last Friday morning. Council colleagues also said they were surprised to hear he had been suffering from stress.
The process of choosing a new leader at Glasgow City Council will begin later in the year, probably after the general election. Until then, the role of acting leader will be performed by Mr Purcell's deputy, Jim Coleman.
It was also reported last night that Mr Purcell's PR team had been forced to raise the possibility of a referral to the Press Complaints Commission over the level of media interest in the councillor's case.
• Secluded countryside retreat that uses celebrated treatment to help patients