• All change: from tourism to alcohol, several sectors could now face new levies under the powers proposed by the draft Scotland Bill
Launching legislation described as the biggest transfer of power to Scotland since the United Kingdom was formed, Moore was in expansive mood when discussing the benefits to be derived from an updated devolution settlement for Holyrood.
Then he was hit by a difficult question. One person attending his press conference in the old building that once housed the Scottish Parliament had picked up on a small line in the Bill that was almost buried by the legalese and technical detail.
Among those huddled in the hall's "black and white corridor", the main thrust of the Scotland Bill - a new Scottish income tax system and borrowing powers - was an open secret. But the new development, which was about to make Moore stumble on his words, was a line saying that the Scottish Parliament would be able to introduce "new Scotland specific" taxes, over and above those singled out in the Bill.
"So what sort of other taxes would be introduced to Scotland?" was the question Moore was asked.
"Well... errrr... perhaps a plastic bag tax," Moore replied. "They have that in Ireland, you know," he added, before swiftly moving the discussion on to more comfortable ground.
The full variety of extra taxes that could come Scotland's way with the passage of the Scotland Bill was potentially much more than a plastic bag tax, and they appeared not to feature on Moore's radar. The stately progress of the Commission, the body set up by Labour, the Lib Dems and the Conservatives, ensured Calman students were well aware that a new income tax arrangement, allowing Scotland to raise over one third of the revenue it spends, was on its way.
Similarly, the creation of borrowing powers were part of Calman, although the 2.7 billion limit was larger than expected.
Likewise, the Bill's moves to give MSPs control of landfill tax and stamp duty as well as justice powers covering the control of air guns, speed limits and drink-drive laws were widely predicted.
Behind the scenes, however, the full range of other taxes that could come to Scotland as a result of the new legislation have been discussed by politicians and academics for some time. The ability to introduce a host of new financial instruments will define the political debate over the coming years as all parties look at new ways of raising money as Scotland's 30bn budget shrinks.
In as far as his answer went, Moore was correct - a plastic bag tax could become a reality in Scotland. In Ireland, the levy has raised millions of euros and helped the environment by cutting down on plastic bag use.Here, however, there is already a tide of opinion suggesting that this latest incarnation of Calman can go much further than just plastic bags.
Wendy Alexander, the former Scottish Labour leader who set up the Calman Commission, is one influential politician who would appear to recognise a far more imaginative and varied taxation system could be introduced in Scotland in the long term.
Scotland on Sunday understands that Alexander, who this week will be announced as the convener of an ad hoc Scotland Bill committee at Holyrood, has been taking great interest in papers prepared on that very subject. As the convener of the committee that will prepare the legislation for scrutiny at Westminster, Alexander has been examining a paper recently written by John Aldridge, a former Scottish Executive finance director, on changes to Scotland's taxation system.
In an article published by the David Hume Institute, Aldridge suggests that there is "a more radical option" than simply setting a different Scottish income tax rate. Anticipating the Scotland Bill, he writes: "The Scottish Parliament is expected to be given the power to create new taxes on the agreement of the UK parliament.
"Perhaps the most obvious possibility would be the introduction of some kind of tourist or tourist bed tax. Such taxes are quite common elsewhere and there would be less risk of adverse consequences from a divergence of taxation practice between Scotland and the rest of the UK in this area. Although the tourism industry would no doubt object to the concept."
Aldridge, who was on the expert finance committee that advised Calman, suggests that a 1 a night tourist tax would raise 70m a year.
One idea being kicked around would be using a tourist tax to resurrect Scotland's Route Development Fund that was set up to give airlines an incentive to create Scottish services. The RDF was dropped by the SNP when Alex Salmond became First Minister. But the theory is that the new flights to and from Scotland would offset the damage to the tourism industry from a tourist tax.
"It's [a tourist tax] been looked at, but I don't think we've got a commitment to it," said Robert Brown, the Lib Dem MSP and a member of Alexander's Scotland Bill committee.
"It has been said as an option that cities might take on. If, for the sake of argument, Edinburgh, Glasgow, Aberdeen wanted to do that in order to improve tourist facilities. There might be some options that way. That would be a possibility for the Scottish Parliament if it was felt there was meat and drink in that direction of travel."
Looking into the future, other options up for grabs include using the new powers to create an alcohol social responsibility levy that could divert the cash raised straight back into the NHS; a Scottish graduate tax to finance higher education; and a land tax, which would require all owners of land, rural and urban, to pay annually in accordance with the rental value of the land.
One other suggestion made by Aldridge would be for some income tax diverted to local government spending - a system similar to the local income tax that the SNP failed to get through parliament.
Of course, any suggestion of new taxes are highly sensitive politically. Given that the new income tax powers cannot be exercised until 2015, it is unlikely any of the main parties will go into next year's Scottish election with promises to levy new taxes on their manifestos.
But at some point there will be serious cross-party discussions and engagement with the academic sector to look at these issues, and arguments over new taxation methods look likely to dominate the political landscape in the years to come. In the immediate future, however, Alexander's committee, which meets for the first time on Tuesday, is likely to be dominated by more traditional Calman fault lines.
Although Scotland will receive more powers as a result of the Bill, the SNP maintains that it does not go nearly far enough. Salmond has condemned the Bill as a "lacklustre… a Calman minus" that "tinkers round the edges" of the issue.
As advocates of Full Fiscal Autonomy, a settlement whereby Scotland has responsibility for all existing taxation, the SNP members of Alexander's committee - Brian Adam and Tricia Marwick - will be looking to bolster the Scotland Bill.
"Basically we want to improve and strengthen it, particularly in the financial measures which we regard as puny," said an SNP source. "That is the purpose of parliamentary scrutiny. This legislation will still leave 85 per cent of Scottish revenue under the ambit of Westminster."
In addition to lobbying the committee to increase the powers destined for Holyrood, the SNP will also be looking at what it regards as the more "eccentric" aspects of the Bill.
For example, the idea that the Scottish Parliament will be able to set a speed limit for cars, but not for cars towing caravans; and the airgun legislation, which means that control of the most dangerous air weapons remain reserved to Westminster.
The SNP will also call for the aggregates levy, a tax on quarrying worth 50m-a-year, and air passenger duty, worth 100m, to be devolved. Originally, Calman had recommended that those two instruments ought to be handed to Scotland.
However, it is the income tax proposals that will be the source of most SNP fire and fury. In committee, the SNP will argue that the new arrangement would see Scotland lose out on income tax receipts.
The Scottish budget will be assigned half the income tax raised at the basic rate, one quarter of the revenue raised at the higher rate and just one fifth of the cash from the new top rate. Given that higher rate taxpayers tend to account for a larger share in the growth of tax receipts Scotland stands to lose out if the Scottish economy improves.
The SNP may talk of strengthening the Scotland Bill, but how realistic are its ambitions? After all, its two committee members will be outnumbered by Liberals, Tories and Labour MSPs who have signed up to the Calman process. The Liberals may have made noises about lobbying with the SNP for an enhanced "Calman Plus". But now the political reality is that Tavish Scott is tied into the current version of the Scotland Bill with the Tories and Labour. There appears to be little wriggle room on that front.
Ultimately, the SNP says the best chance it has of converting Calman constitutional change into full fiscal autonomy is by performing well at the ballot box next year.
"The Scotland Bill will feature very prominently in the election," the SNP source said.
"If people think the Scotland Bill should remain as it is, then they can vote for Labour, the Lib Dems or the Tories. They are all joined at the hip on this one.
"But if they believe the Scotland Bill is not ambitious enough then the SNP are the clear alternative."
Yesterday, Marwick pledged that she would "make sure that the Scotland Bill acts in the best interests of the people of Scotland".
"That's what I'll be focused on," she added.
It was under duress from the Liberal Democrats that the Scottish Government agreed to take part in the Calman process as a concession to getting last year's budget through. Having participated, albeit reluctantly and minimally, with the Calman process it follows that Marwick and Adam will engage with Alexander's Holyrood committee. But it still remains to be seen whether the SNP will support a Labour, Conservative, Lib Dem piece of legislation that promises a more powerful Scottish Parliament short of their ambitions.
Alexander said of the Nationalists: "For them to regard this as a backward step is simply incredible. But, of course, twice it has come before the parliament they have voted it down, so the question is: are you going to be on-side or off-side this time round?"