THE new Scotland Act would be the right "resting place" for Holyrood's devolution settlement, David Cameron declared. He was speaking in January as a set of draft clauses, since refined into the Bill that is before parliament, was published in Edinburgh.

His language, for the most part, was bullish. The codified conclusions of the Smith Commission were "built to last," he told an audience of civic leaders. This was "a great day for Scotland and a great day for the United Kingdom too". Holyrood would become "one of the most powerful devolved parliaments in the world". A strong Scotland within the safety and security of the UK, he said, "Scotland spoke, we listened, and now here we are delivering," he concluded, referring to the pre-referendum "vow" to bring forward an agreed package of tax, welfare and borrowing powers.

But it was that phrase, "resting place," that stuck in the mind. Did it betray a private suspicion the deal was heading for an early grave?

The ink is hardly dry on the Scotland Bill but debate about a longer lasting constitutional arrangement is livelier than ever. After the straitjacket of the independence campaign, when Scots were presented with a choice between a beefed up Holyrood and the version of independence that was revealed in the Scottish Government's white paper, Scotland's Future, a space has opened up for a much freer consideration of the future shape of the UK.

Pat Rafferty, the Scottish Secretary of Unite, this week reminded Labour of his union's support for a form of "devo max" that could have come close to the SNP's system of full fiscal autonomy.

The SNP, meanwhile, continues to back away from full fiscal autonomy. Interviewed on the BBC's Daily Politics, Pete Wishart said it was an "aspiration". It was clear from his answers the SNP would only be interested if full fiscal autonomy could be delivered without making Scotland £8billion worse off, as the IFS think tank has calculated. The Perth and North Perthshire MP's priority was to devolve

National Insurance Contributions to Holyrood.

Gordon Wilson, the former SNP leader, went one further, claiming the party was not only sidelining full fiscal autonomy but independence too. Controversially, he claimed the party was shifting towards federalism. Ridiculed though this will be, there is a logic to his thinking. As he argues, Nicola Sturgeon's call for a "double majority" in the forthcoming referendum on the UK's membership of the EU is distinctly federalist in approach.

Mr Wilson saw this as "strategically

dangerous since it

supersedes Scottish

sovereignty with a

British federal sovereignty". He wants all this federalist mess cleared up at the next SNP conference, by the way.

Ms Sturgeon's approach to the EU referendum (if not her specific demand for the double majority) is shared by Labour's First Minister of Wales, Carwyn Jones, whom she entertained at Bute House on Wednesday.

In a federal-flavoured joint communique, the two leaders agreed that "any decision to leave the EU, taken against the wishes of the people of Wales or Scotland, would be unacceptable and steps must be taken to ensure this does not happen".

It is not clear where things are going. But it is clear debate is spreading well beyond the Smith Commission proposals and fiscal independence.

It has even reached as far as Scottish Labour, the most cautious of all the parties on extending devolution in recent years. A Labour for Federalism campaign is about to be launched, in a bid to pull the party towards a more radical, lasting constitutional settlement for the whole UK. One of the people behind it, Michael Marra, the former party strategist and candidate, believes it will appeal to those within the party who have long been federally minded and to those who have come to the conclusion that Labour can no longer afford to be dragged from one constitutional concession to the next. The campaign will not put forward a detailed blueprint for how a federal UK might operate - to begin with at least - though the vision will include a reformed House of Lords, greater devolution to the English regions and perhaps an English parliament to balance greater autonomy for Scotland, Wales and Northern Ireland. The UK would provide a "common safety net" in terms of pensions and social security. Mr Marra reckons such an arrangement would succeed because it is what people actually want. It will be interesting to see what his colleagues think. Especially those who might become leaders of the Scottish and UK parties.