We thought you might be interested to see some of the working of this post from yesterday. Of the 2.4m votes cast in Scotland in the 2010 UK general election, not far short of a million – if a recent YouGov poll is to be believed – are currently likely to be cast for different parties in 2015. And it’s intriguing to see where they’ll go.

NB The poll had an “Other” category which didn’t specify UKIP, Green, SSP etc. The overall split of those three parties’ votes broke down in a ratio of 6:4:1 (in that order), but there was no mechanism for determining whether, say, Labour voters planned to defect more to Green/SSP and Tory voters to UKIP. So readers will have to make that judgement for themselves.

PROJECTED DESTINATION OF 2010 LABOUR VOTES IN 2015

Labour: 579,896 (56%)

SNP: 331,369

Other: 72,487

Conservative: 51,776

Lib Dem: 10,355

For all Labour’s endless decades of screaming “Tartan Tories!” at the Nats, the fact is that the latter remain the first port of call for dissatisfied Labour voters, picking up more than six times as many Labour defectors as the Conservatives.

PROJECTED DESTINATION OF 2010 SNP VOTES IN 2015

SNP: 402,397 (82%)

Other: 34,397

Conservative: 34,397

Labour: 19,655

Lib Dem: 0

While Labour has shed over 40% of its vote, the SNP holds onto more than 80% of the people who backed it in 2010, with the rest splitting reasonably evenly between everyone else except the poor old Lib Dems.

PROJECTED DESTINATION OF 2010 LIB DEM VOTES IN 2015

SNP: 195,498

Lib Dem: 97,749 (21%)

Other: 88,439

Labour: 65,166

Conservative: 23,274

Oooft. You know it’s bad when you can’t even take the highest vote share among your own supporters. In fact, twice as many Lib Dem voters from 2010 plan to defect to the SNP next year as to stay with Nick Clegg’s dead party walking. Labour can’t even manage third place, and we honestly wouldn’t like to speculate about the UKIP/Green split among the “Other” section.

PROJECTED DESTINATION OF 2010 CONSERVATIVE VOTES IN 2015

Conservative: 280,741 (68%)

Other: 57,800

Labour: 37,156

SNP: 28,900

Lib Dem: 12,386

On the other hand, we suspect we can make a pretty good stab at which horse Tory defectors to “Other” will be backing. But it’s worth noting that more former Tories find Labour a better fit for a switch than the SNP. And interestingly, the Tories pick up almost twice as many votes from their coalition partners as move the other way. Because people tend to hate the bully’s toady more than they hate the actual bully.

It’s remarkable that the party which has carried the burden of government for seven and a half years – pretty much all of it through a tough recession – appears to have by a considerable distance the most loyal voters. Conversely, for the main opposition party, free of responsibility on either side of the border, to have driven away close to half of its own support is an astonishing feat of incompetence.

(A survey this month by the Unite trade union produced even worse findings, with an astounding 54% of 2010 Labour voters – at least those defined by unspecified criteria as “working people” – saying they didn’t expect to vote Labour again next year.)

But perhaps the most striking fact about these figures is that Labour isn’t the first choice for defectors from ANY of the other parties. The SNP and “Others” hoover up the biggest share of vote-switchers across the board, and – combined with the UKIP phenomenon south of the border – that could be a sign of the most radical change in UK politics in living memory.

After several false dawns, the UK may finally be about to witness the extinction event marking the end of the two-party dinosaur age.