MORE than a month after the SNP tsunami struck, it is still a struggle to comprehend how much of Scotland's political landscape was forever washed away.

Discerning the new landscape emerging since election day is no easy task either.

But yesterday offered more pointers to the profound changes underway.

In Glasgow's George Square, thousands of anti-austerity marchers protested against the unbridled cuts of a Tory majority government. The unions were to the fore.

In days past, those unions would have been synonymous with Labour - and Labour only.

But it was Nicola Sturgeon who sent her support from Stirling, and said the SNP would make "common cause" with the trade union movement in a speech about workers' rights.

Moreover, her audience was made up of trade union members in the SNP.

Since the referendum, the party's trade union group has grown from 800 to almost 16,000.

As we also learned yesterday from a candid Kezia Dugdale, that is around 500 more than the entire membership of Scottish Labour.

The SNP, said the First Minister, had replaced Labour as the party of Scottish working people.

Before the referendum, that might have been dismissed as wishful rhetoric.

But after the collapse in Labour's vote on May 7 - and the shattering of the Labour-voting habit - it does not seem fanciful any longer. The wish has been fulfilled.

When people suffering Tory cuts think of the party that best stands up for them, who is it?

Which party speaks against austerity with the loudest, boldest, least inhibited voice?

Labour may complain the Nationalists have stolen their clothes, but they appear to fit perfectly.

At Westminster too, the SNP boast that they would be the official opposition seemed premature in the immediate aftermath of the election.

But with Labour looking inward as it chooses new leaders, and an early trend of voting with the Conservatives in kneejerk opposition to the SNP, it now seems wholly apt and true.

If Labour want to be Her Majesty's opposition, they should oppose the Tories more - and the party backed by half of Scotland less.

The SNP is not perfect, of course.

Its announcement last week of a government tour asking people to "suggest practical solutions" for a "fairer Scotland" suggested a party strong on elections, but weaker on policy.

After promising to make not just Scotland but the whole of the UK a fairer place, the SNP really ought to have ideas of its own.

But this is for sure: the SNP deserves to replace Labour in the public mind as the party which fights for ordinary people, because it truly is the only opposition to Tory austerity - that's why its support in Scotland is so strong. Likewise, Labour - for abandoning its roots - equally deserves its own self-constructed fate.