IN the early hours of May 8, 2015, a 20-year-old politics student, Mhairi Black, defeated the Labour campaign chief, Douglas Alexander MP, one of the most experienced and highly regarded figures in the UK Labour Party. It was the most dramatic and poignant moment in the most extraordinary general election in Scottish history, which drew the curtain down on Labour's half-century of dominance in Scottish politics.

Alexander’s Paisley seat had been one of Labour’s safest, and the former foreign secretary was not just beaten, but crushed. Black turned a 16,000 Labour majority into a 5,600 SNP majority. It was the same story across Scotland as the SNP went from having only six seats out of 59 to 56 out of 59.

Black had received her share of abuse on the internet and from political rivals during the campaign, as did a lot of politicians – social media has become a curse as well as a convenience in political communication. She had been dismissed as an ingenue, an extremist and even a “foul-mouthed little slut” by an Edinburgh University professor. Black had tweeted “maths are s***e” when she was 16 and confessed to a fondness for Smirnoff Ice.

But she went on to deliver one of the most celebrated maiden speeches in recent parliamentary history: a coruscating assault on social inequality and Conservative welfare reform that attracted 10 million views on the internet within 10 days. The press and even Conservative MPs paid tribute to her as a new parliamentary star.

And she was not alone. Other new SNP members like the Edinburgh East MP Tommy Sheppard and the MP for south-west Edinburgh Joanna Cherry QC, also made impressive maiden speeches in Westminster. The Speaker, John Bercow, was moved to describe them as good parliamentarians – a mixed blessing since the Nationalist MPs had mostly condemned Westminster as a bastion of the Tory establishment.

The Tsunami election of 2015 was well-named. Labour were simply swept away losing 40 of their 41 seats. Out went the party's Scottish leader, Jim Murphy, who had spent a lot of Labour's political and financial capital in trying to outflank the SNP on the left. The other Unionist parties did little better. The Tories retained their sole Scottish MP, David Mundell, in Dumfriesshire, Clydesdale and Tweeddale, but recorded their worst share of the vote in Scotland in a century, even as the party won in the UK.

The Liberal Democrats, who had been a strong presence in the Highlands and in parts of the Borders, were wiped off the Scottish mainland. Their only man left standing was Alistair Carmichael in Orkney and Shetland. The former Scottish Secretary scraped home with a majority of 817 votes, and ended up in court accused of lying during the campaign about a leaked civil service memo traducing the SNP leader, Nicola Sturgeon.

The real tragedy for the party, however, was in Ross, Skye and Lochaber where the former Liberal Democrat leader, Charles Kennedy, lost another safe Libdem seat. Within weeks the chat show star and Glasgow University Rector was dead at only 55 following an alcoholic haemorrhage. Scotland mourned the loss one of its most popular politicians.

The magnitude of the swing to the SNP was simply unprecedented in UK electoral history. Normally, general election swings are in single figures, and a shift to any particular party of 10 per cent is rare. In the 2015 general election the average swing to the SNP across Scotland was 30 per cent.

Glasgow North East, a Labour seat that political commentators believed was impregnable, fell on a swing of 39.3 per cent, and broke the BBC’s swingometer. The safest seat in Scotland was actually the former Labour prime minister, Gordon Brown's former citadel in Cowdenbeath where he had returned a 23,000 majority in 2012. This fell to the relatively obscure SNP candidate Roger Mullin, with a 10,000 majority on a 37.9 per cent swing.

The SNP had never won a Westminster seat in a general election in Glasgow before; now they hold all seven. They won all but one seat in Edinburgh and Fife. The Highlands and the Borders turned SNP yellow, leaving only a patch of blue in Dumfries.

I make no apologies for hammering home the magnitude of the SNP victory. It was so comprehensive that in a way it suffered from being under-reported. I don't think this was so much Unionist bias in the media as superlative fatigue. After you observe that Nicola Sturgeon had won everything, there's very little left to say. I still come across people in Westminster and the London media who are unaware of the sheer scale of the Nationalist sweep.

However, political scientists will be marvelling at these figures for many years, since they represent an almost evangelical conversion by the voters of Scotland to the Scottish National Party. How could this diverse political culture suddenly swing overnight to Nationalism? And less than a year after Scotland had rejected independence in the 2014 referendum.

The big story, however, for most of the UK press and media was David Cameron's unexpected victory in the UK. Few had thought even in the Tory party that the Conservatives were on course to win an overall majority in the 2015 general election. Another coalition with the Liberal Democrats seemed on the cards. But thanks to the implosion of the LibDems under Nick Clegg – and the waning of Labour under Ed Miliband – David Cameron found himself hailed for winning the first full Conservative general election victory in 23 years.

A more volatile aftermath could scarcely have been foreseen: a Conservative majority government in Westminster, with the most right-wing programme in decades, and an SNP landslide in Scotland, led by the social democrat Nicola Sturgeon. Scotland and England had been diverging for many years, but never had the gulf in political culture between the two countries been so stark. The map shows a pure yellow Scotland and a true blue England.

The First Minister insisted that the UK Government would have to recognise the scale of the Nationalist victory and offer more devolution than was contained in the Scotland Bill, which implemented the pre-referendum “vow” and the recommendations of the Smith Commission. She was to be disappointed. None of the SNP amendments to the Scotland Bill were to see the light of legislative day.

However, the 56 Scottish MPs made a strong impression in the early weeks of the new parliament, defying Commons conventions and being censured by the Speaker for applauding in the chamber (though following Hilary Benn's speech on Syria, clapping seems to be catching on in Westminster).

Alex Salmond, returned to the Westminster debating chamber he loved as the new MP for Gordon, lost no time in making his presence felt in debates and at Prime Minister's Questions. But fears that he would become a truculent and headstrong rival to leader Nicola Sturgeon turned out to be unfounded. She is still very much the boss.

The SNP were now the third party in the House of Commons, taking over the corridor of the Palace of Westminster formerly occupied by the Liberal Democrats – and perhaps most remarkably of all, securing the chairmanship of the Scottish Affairs Select Committee. They claimed credit for forcing David Cameron to abandon plans to abolish the Human Rights Act and restore fox hunting in England, even though Nicola Sturgeon had once said this was a matter solely of interest to English voters.

And during the debates on the Welfare Bill in July, the 56 SNP MPs infuriated Labour by physically occupying the Opposition benches. Harriet Harman, the interim Labour leader following Ed Miliband's resignation, had advised Labour MPs to abstain and consequently they had largely vacated the chamber. Many Labour Party members were appalled at this apparent capitulation to welfare reform. It's arguable that this was the moment when Jeremy Corbyn gained real momentum in the Labour leadership contest as party members turned against the right-wing leadership.

However, despite these early presentational successes, it was to be a frustrating time for the 56 SNP MPs. They were unable to make a significant impact on the Scotland Bill introducing new tax powers to Holyrood as it trundled through the autumn. It became clear that the Scottish Parliament was being given just enough fiscal rope to hang itself, by getting the power to raise only income tax to mitigate Conservative welfare cuts. Other sources of revenue – wealth taxes, national insurance, corporation tax etc – would remain with Westminster.

Then there was resignation and embarrassment. The 56 became rapidly reduced to 54 following the resignations from the party of two of the most prominent women in the entire independence movement: Michelle Thomson, the former director of Business For Scotland, MP for Edinburgh West, and Natalie McGarry, the new MP for Glasgow East and one of the founders of the influential pro-independence group, Women for Independence.

Michelle Thomson was forced to walk after it emerged that the lawyer who had advised her in her property business had been suspended by the Law Society for behaviour which indicated possible fraud. He had been involved in back-to-back deals under which properties are bought below market value from distressed sellers, and then sold on for a higher sum within hours or days.

No wrongdoing on Ms Thomson's part has been established. But some clients who had sold their property to her company complained in the press that they had been cheated. This has made it difficult for the party to reinstate the former business spokeswoman without sparking another round of negative press stories.

The Natalie McGarry case is even more difficult. She resigned the SNP party whip after senior figures in Women for Independence (WFI) called in the police to investigate the loss of funds from the Women for Independence Paypal account which was in her name. Tens of thousands of pounds had been raised by crowd-funding. Yet a large proportion of this was apparently unaccounted for.

Again, no actual wrongdoing has been established, which leaves the SNP in a very awkward place. Natalie McGarry is a long-time party activist and was marked out for a prominent role in Westminster. But it seems hard to see how she can be rehabilitated when it was a unanimous decision by the national committee of WFI – five of whom are SNP candidates – to refer the situation to the police.

These controversial figures will continue to overshadow the work of the other 54 SNP MPs. The two MPs are suspended from the SNP Party whip, but have every right to remain in their Westminster seats. Under our parliamentary system, it is the individual, not the party, that is elected in a general election contest.

Rival parties have been keen to accuse the SNP leadership of failing to scrutinise its candidates properly and Nicola Sturgeon of failing to take action earlier. Mind you, there is no indication that the scandals have damaged either Ms Sturgeon or the SNP. The party continues to dominate the opinion polls in Scotland, much to the chagrin of the new Labour leader, Kezia Dugdale.

Labour underwent something of an internal revolution following Ms Dugdale's comfortable win in the Scottish Labour leadership election in September. She declared that the Scottish Labour Party, while still constitutionally part of UK Labour, would have its own policy agenda, even on reserved issues, and that the Scottish Labour Party Conference would become a genuine policy-making body.

This led to what was widely hailed as the most controversial and lively Labour conference in decades at the end of October when the party voted overwhelmingly to oppose the renewal of the Trident nuclear weapons system. It also voted against the Transatlantic Trade and Investment Partnership (TTIP).

Dugdale has fully exploited the increased autonomy granted by the new UK Labour leader, Jeremy Corbyn. His victory had distinct echoes of the Scottish referendum campaign. It was an influx of new members to the Labour party, radicalised by the financial crash and informed through social media, that turned the party so dramatically to the left. Like the cybernats, many “Corbynites” were combative on the internet and were accused of abusing right-leaning Labour MPs like Mike Gapes and Stella Creasy on Twitter.

So, the reverberations from the Scottish Tsunami have been felt across the entire United Kingdom in 2015. It seems hard to believe that the UK constitutional status quo can endure when Scotland has voted so massively for the party of independence. However, this does not mean that Scotland is going to have a repeat independence referendum any time soon. Nicola Sturgeon made that clear at the biggest SNP conference in history, in Aberdeen, attended by 5,000, that her priorities are education and health.

The SNP is leery of another referendum fearing that, despite the General Election, the result might not be all that different from 2014. Sturgeon's priority for the medium term is securing her personal mandate in the Holyrood elections in May. For all her achievements, the First Minister of Scotland has never actually been elected by the Scottish voters. But with the latest TNS opinion poll indicating that the SNP is in line for another landslide of 78 out of 129 seats, she may not have to wait long to tick that box.