When the Spanish Prime Minister Pedro Sánchez took to the stage at his party’s election night rally in Madrid last Sunday, you could have been forgiven for thinking they had won Spain’s general election.

Sánchez’s Partido Socialista Obrero Español (PSOE), the British Labour Party’s Spanish sister party, had lost their status as the single largest party in the Congreso de los Diputados, the lower chamber of the Spanish legislature, to the conservative Partido Popular, who gained 47 seats.

But the Partido Popular’s victory was a pyrrhic one. They fell far short of the 176 seats needed to form an absolute majority, and even with the support of smaller right-wing parties like the far-right Vox and centre-right regionalist parties, they would lose the investiture vote required to form a government.

Sánchez had called the snap poll following local and regional elections in which his party had lost control of dozens of municipalities and provinces to the Partido Popular. National opinion polls were pointing to a right-wing majority between the Partido Popular and Vox, and across Europe hands were beginning to be wrung over the prospect of Spain’s first far-right governing party since the death of fascist dictator Francisco Franco and the transition to democracy in 1975-8.

Sánchez fought the election, in his own words, as a “showdown between the forces of progress and the forces of reactionary conservatism”. A showdown in which the Spanish left prevailed by depriving the Spanish right of the seats needed to govern.

As Sánchez declared that victory before his party’s assembled supporters and activists, he was briefly drowned out by their chants of “no pasarán” – “they shall not pass”, a slogan most associated in Spain with the fight against fascism in the Spanish Civil War. The meaning of the election result, for the Spanish left at least, is clear.

But there may be deeper lessons to be learned from specific results in this election, notably the PSOE’s comeback in the hitherto secessionist-dominated region of Catalunya.

In Catalunya, the PSOE’s Catalan party, PSC, achieved their best result since 2008. They increased their share of the vote from 20.5% in 2019 to 34.5%, gaining an additional seven seats to win 19. The main Catalan secessionist parties, Esquerra Republicana de Catalunya and Junts per Catalunya, won 24.4% of the vote and 14 seats.

Between them, the PSC and their left bloc partners, Sumar, now control most of Catalunya’s 48 seats. The PSOE also managed their best results in 15 years in the secessionist Basque Country.

Three factors of interest helped the PSOE stage comebacks in Spain’s secessionist regions that Labour might want to consider as they attempt a similar comeback in Scotland.

Firstly, Pedro Sánchez’s government from 2020 onwards marked a significant shift in the Spanish state’s attitude towards its secessionist regions. The 2017 Catalan independence referendum was marred by violent clashes between police and activists, the suspension of Catalan autonomy, and Madrid’s imposition of direct rule. The Spanish government pursued charges against Catalan leaders involved in the illegal referendum, and several went into self-imposed exile.

As Sánchez sought to put together a governing coalition following the November 2019 general election, his party spent two months negotiating with Esquerra, culminating in a pact including formal talks between Barcelona and Madrid on Catalunya’s constitutional status and rights within the Spanish regime.

Those talks began in February 2020 in a meeting in which the two sides agreed that the Partido Popular, not Catalunya’s nationalists, bore responsibility for the 2017-18 constitutional crisis.

A separate pact with Basque secessionists included commitments to strengthen the Spanish state’s recognition of territorial and sub-national identities and the transfer of greater powers to Navarra – a region with a significant Basque minority.

Sánchez’s accommodationist approach to Spain’s secessionists provides something of a safe haven for left-leaning soft nationalists in regions like Catalunya. In sharp contrast, Vox, which the Partido Popular would have depended on to govern, wants to ban political parties with secessionist aims.

This brings us to a second factor, that Sánchez’s explicit and loud opposition to the right is a strong rallying cry in regions with leftist traditions, like the Abertzale left in the Basque Country, and strong anti-Francoist traditions, as in Catalunya.

It is unlikely that a more compromising approach to the Spanish right would have been so successful in regions now so instinctively averse not just to Vox but to the Partido Popular too.

Lastly, while Sánchez has accommodated Spain’s secessionists, he has done so “within the constitution” without even entertaining the prospect of conceding independence referendums.

As the prospect of future state-sanctioned routes to independence has weakened, support has bled away from Catalunya’s secessionists. Turnout in Catalunya fell by nearly four points in this election, in contrast to a trend of the same magnitude in the opposite direction across Spain.

And this drop in turnout seems to have had a differential effect, disproportionately hurting secessionist parties as some hardline supporters stayed home – the far-left secessionist party, Candidatura d’Unitat Popular, saw their vote share more than halved and lost both their seats.

Sánchez’s willingness to take the fight to the political right, recognise the legitimacy of and accommodate regional nationalisms, and do so while maintaining a constitutional firewall that keeps secession off the agenda deprived secessionist parties of a credible unique selling point while also giving sections of their support reasons to switch to the PSOE.

His strategy has proven a political cocktail capable of reviving his party’s fortunes in secessionist regions where they were once strong contenders.

Right now, Labour is doing its best to deprive the SNP of the unique selling point of Scottish independence but is doing little to appeal to Scotland’s left-leaning, soft nationalists. Maybe that will be enough to gain ground, but I doubt it will be enough to supplant the SNP.

There are many differences between Scotland and Spain’s secessionist regions, notably that Scotland’s secessionists are stronger and more unified. To break the SNP’s grip, Labour could do worse than learn from Pedro Sánchez and their Spanish sister party.