Nicolaides, 41, had a tearful reunion with his father Socrates, brother Forde and partner Jintana at Melbourne Airport having been deported shortly after his midnight release from jail.

Nicolaides was sentenced to three years' jail after pleading guilty to lese majeste - offending the royal family - in 12 lines he wrote in his 2005 novel Verisimilitude, which referred to an unspecified crown prince's love life. The novel sold only seven copies.

He gained his freedom by royal decree from King Bhumibol Adulyadej. Asked how he felt after his flight to freedom, a gaunt-looking Nicolaides said "bewildered and dazed, nauseous".

"I have been crying for eight hours. I learned only a few minutes before my flight that my mother had suffered a stroke," he said.

"A few hours before that I was informed I had a royal pardon and asked to kneel before a portrait of the king - a royal audience of sorts. A few hours before that I was climbing out of a sewerage tank that I fell into in the prison."

He said he "ran out of tears [in jail] but I never ran out of hope or love". But he was tired. "I am exhausted and I have a mother to go and see who suffered a stroke and has lost the power of speech," he said.

His father Socrates said he was delighted to have his son back.

"It was a living death but now I feel I have come alive again," he said.

Nicolaides's lawyer, Mark Dean, SC, said his client was locked up as part of a ploy by the former Thai government to appear tough on critics of the country's monarchy.

"I think it's fair to say that Harry was a political prisoner, and that the reasons for the commencement of this case against him were inextricably linked to the political crisis in Thailand in August 2008," Mr Dean said. "But since then, conditions have changed in Thailand, there has been a change of government, and the current Thai Government has done everything it can to support Harry's case."

Despite claims months ago that the Australian Government had not done enough to support his release, Nicolaides praised the role of officials. "I am happy with the Australian Government's efforts," he said.

Opposition foreign affairs spokeswoman Julie Bishop welcomed news of the homecoming.

"The imprisonment of Mr Nicolaides has been a traumatic experience for him and his family, particularly his elderly parents," she said. "We are relieved that the appeals for clemency have been given sympathetic consideration by the [Thai] king."

Earlier this month, Nicolaides revealed the horror of his incarceration in The Sydney Morning Herald.

"We are woken at 6 and counted in the cell. Mine is 12 metres long and just over four metres wide, holding 50 or 60 prisoners, mostly Thais, mostly murderers and rapists. The cell has one toilet, which is a hole in the ground, and poor ventilation. I sleep in a face mask because tuberculosis and pneumonia are common," he said.

He said the food was "mostly fish bones in hot water, extremely spicy, with rice. I've tried it and felt unwell ? There are 20 or 25 cats that run into the mess hall before the prisoners. Some men put cigarettes in the cats' mouths or do other unspeakable things to them".

He was barefoot most of the day, partly so he couldn't climb the electrified, barbed-wire fence, partly through custom.

"The floors are covered with fish bones, saliva and cat vomit, so my feet are black. I am led to court in shackles and chains. It's positively medieval."