Left-wing campaigner Tommy Sheridan hopes Thursday will mark his return to the Scottish Parliament.

He is running on a robustly pro-independence ticket, pledging a re-run of the referendum in 2018 and urging Yes voters to beware caution and complacency.

When we sit down to speak about his chances on Thursday, I ask him if pushing a second referendum so soon is a wise strategy. A second No, still not a far-fetched possibility, could bury independence for generations -- actual, real generations.

Sheridan, however, is impatient for change and points to the impact of Conservative government policies on disadvantaged people in Scotland.

He tells me: "We started off the referendum campaign, around 2012, with roughly mid-to-late-20s support for independence. By the time we got to September 18, 2014, we had risen to 45%, despite the blizzard of lies and bullying and distortions from the British establishment and their media hirelings, particularly, I'm afraid, across the way there at the BBC.

"I think starting with 45%, we will easily get to 60%, 65%. The reason I think 2018 is not too soon is because we have to be very aware of the victims of austerity. The victims of austerity are the vulnerable, the disabled, the unemployed, the low-paid, the children with low attainment in overcrowded schools and under-resourced schools. We have to think about them. They can't wait any longer than 2018.

"Some people in the Yes movement would argue that 2018 is too far away. (By the way, there are legitimate arguments to back that.) I think 2018, given that we've got an election right now, gives us the possibility of a mandate... for all the pro-independence parties. See if all the pro-independence parties together don't get over 50% of the popular vote on May 5, we don't have a mandate. It's that simple; we don't have a mandate.

"But if all of the pro-independence parties collectively manage to get over 50% of the vote in the elections on May 5, that for me is a mandate for a referendum in 2018 and when we win that referendum in 2018, we give ourselves a maximum two-year period to negotiate the disengagement from Westminster; to negotiate our share of British plc's assets, which is significant, and we set the date April 6, 2020 -- 700 years to the day of the Declaration of Arbroath -- that's when we declare Scottish independence."

Sheridan has come to be associated with the independence movement in recent years but to most voters he is still the clenched-fisted left-winger of days gone by. The working class organiser rose to prominence with his resistance to the poll tax, activities that ended in a prison sentence for contempt of court.

In 1999, he was elected to the first Scottish Parliament as leader and sole representative of the Scottish Socialist Party and after an anti-Blair pitch in 2003 found himself with five new colleagues.

It seemed the stars were finally aligned for a united left, and one that spoke the language of ordinary punters. Revelations in the News of the World that Sheridan had visited a swingers' club in Manchester scuppered these hopes, or rather Sheridan's insistence on denying the claims.

This forced him to sue the tabloid for defamation, an action which he won, but soon he was back in court when the Crown suspected perjury in the original case. Sheridan was found guilty and jailed. He led his supporters out of the SSP to form Solidarity, a party which advances almost identical policies.

The firebrand radical hopes 2016 is the year of his return to Holyrood. While independence is his number one priority, he also has ambitious plans for a more egalitarian society in the meantime. Central to this goal is a more progressive income tax policy.

He explains: "We believe that taxation has to be redistributive. We believe that taxation has to be fair but it has to be used as a tool to make society more equal. That is why we would have a top rate of taxation of at least 50p for the top earners in society. I reject the idea that the SNP have used that we can't increase tax to 50p because people might leave. If that's the attitude, give them their passports; let's pay for their bus fares. I'm not interested in our taxation policies being dictated by the rich.

"I think we should be prepared to have at least a 50p rate but we would go further than that, because we have a Scottish Service Tax proposal. I introduced the Scottish Service Tax Bill in 2006, which would have replaced the Tory council tax. The Scottish Service tax works by setting up five different bands of income-related charges, so that we charge those on incomes around £10,000 or £12,000 a year no taxation; then we have a level of taxation for those on £12,000 to £25,000, £25,000 to £35,000, etc, up until £90,000 a year.

"When we get to over £90,000 a year I make absolutely no apology for the fact that the rate of taxation then will be over 60%. Marginal, obviously; it's marginal rates of taxation. What the Scottish rate of tax does then is it raises more money than the council tax does but it raises it in a fairer and more radical and more redistributive fashion."

In criminal justice policy, Sheridan champions a cause that even some of his sharpest opponents would endorse: The repeal of the Offensive Behaviour Act. The legislation, introduced to curb sectarian singing at Old Firm matches, has come under fire from civil liberties campaigners for its criminalisation of speech, such as expressions of Irish republican identity or cultural Protestantism.

He says: "The Offensive Behaviour at Football Act is a sham. It's a piece of legislation that reminds me of the Dangerous Dogs Act, a piece of legislation that was brought in as a reaction to some terrible attacks that took place in relation to dogs in England. Everybody said: 'We need to do something! Let's introduce the Dangerous Dogs Act!' It was an absolute joke piece of legislation and so is the Offensive Behaviour at Football legislation. Completely and utterly useless. All it's doing now is criminalising football fans for the crime of being football fans. What songs can you sing? What chants can you use?

"Every cloud's got a silver lining and maybe the silver lining in the cloud of the Offensive Behaviour at Football Act is that it's actually brought football fans together from across various divides. It's not just one section of football fans who want to get rid of it; all football fans want to get rid of it. I would argue, as a Celtic fan, that Celtic fans have been more victimised than any section of supporters but they're not the only section of supporters to be victimised. The idea that a Palestinian flag, the idea that a James Connolly flag is somehow or other offensive; the idea that you can't sing about Ireland's history -- I think those things are just wrong.

"I think it's a step too far towards the 1984 type of society that George Orwell talked about. We have to remind some of the legislators that George Orwell wrote 1984 as a warning, not as a manual."

The cloud that hangs over Sheridan is his conviction for perjury. He was sentenced to three years in prison but maintains that justice was not done and has raised the matter with the Scottish Criminal Cases Review Commission.

He doesn't believe his conviction will deter voters: "I was first elected to politics in Scotland in 1992 from a prison cell. I was elected from prison. I was convicted of contempt of court and in the lexicon of law-breaking that is considered to be one of the worst, showing contempt for court.

"I was serving a six-month jail sentence in Saughton jail and was elected in 1992 to Glasgow City Council and served there for 11 years. I think people are more than capable of making up their own minds about whether they trust me or they trust the peopl e who have thrown the mud at me -- and there's been plenty of those."

Stephen Daisley is STV's digital politics and comment editor. You can contact him at stephen.daisley@stv.tv.