THE Scottish independence referendum of 2014 was lost because nationalists could not convince enough voters that breaking away from Britain would benefit them economically. Survey data suggest that hardly anyone who thought the Scottish economy would be worse-off voted Yes. As the ruling Scottish National Party (SNP) lays the groundwork for another referendum, it has been trying to firm up the economic case for independence. Economic strategy is set to be the talk of the SNP’s spring conference, which begins on June 8th. Before the vote in 2014, nationalists promised milk and honey. That was, supposedly, to be covered by bountiful tax revenues from oil and gas production, which would be seized back from London, which currently takes the spoils. A blueprint published by the Scottish government in 2013 suggested that such revenues could amount to £7bn-8bn ($11bn-12.5bn) per year, enough to give every Scot around £1,500. The slump in the oil price in 2014 put paid to such ideas. Last year the tax take from oil and gas was practically zero. Scotland’s economic growth is weak and is expected to remain slower than that of Britain as a whole (see chart).

All of which should have further weakened the economic case for independence. Yet Brexit, which Scots voted against by 62% to 38%, has shaken things up. In the referendum of 2016, Leavers defied warnings that Brexit would provoke immediate economic collapse—and were proved right. Some Scots feel that they “bottled it” in 2014 and may now be more willing to take a risk, says Chris Deerin of Reform Scotland, a think-tank. And the prospect of rejoining the European Union as an independent country may have strengthened the economic case for breaking away from Britain, in the eyes of some voters. Polls suggest that since the Brexit vote there has been a big jump in the number of Scots who believe that independence would be good for the economy.

The SNP wants to bolster independence economics still further. On May 25th it unveiled a policy paper from its “sustainable-growth commission”, which includes academics and politicians. The 350-page tome often reads like an update to the blueprint from 2013. It likewise contains its fair share of wishful thinking. It repeatedly invites the reader to believe that an independent Scotland could see GDP growth rates of a near-impossible 3.5% a year, without actually promising it—much as a packet of Scott’s Porage Oats suggests, but does not explicitly predict, that you will turn into a kilted hunk if you eat the product.

Still, the document shows that nationalists are taking an altogether more sensible approach to economics. Its forecasts do not rely on oil. Any return from the North Sea fields would, instead, be diverted to what is in effect a sovereign-wealth fund, to be invested in community projects and the like.

The approach to fiscal policy has also become wiser. Official figures suggest that in 2016-17 Scotland raised about £13bn less in taxes than was spent in the country. For now, money coming from London helps make up the difference. But an independent Scotland would stand alone. It would probably inherit a budget deficit of around 6% of GDP. Running such a large deficit over the long term is not a feasible strategy. The policy paper talks of reducing the budget deficit to below 3% in “five to ten years”, hinting that Scotland would limit growth in public spending to one percentage point below the rate of GDP growth. That implies a more austere stance than nationalists have previously advocated. The Scottish left has slammed the report. Richard Leonard, the new leader of Scottish Labour, said that the growth commission would be better named the “cuts commission”.

The nationalists have plenty more work to do to convince sceptical Scots of the economic benefits of independence, which would still represent a massive economic gamble. The report does not offer enough detail on the question of Scotland’s currency, which proved to be the Yes camp’s undoing in 2014. It talks still less about Brexit, and in particular the question of whether the England-Scotland border could really remain frictionless if one country were in the EU and the other not. Nonetheless, in the current climate, a small improvement in the economic case for independence could have a big impact.