03:51: "The flag does not belong to any one party" said a defeated Jim Murphy, somewhat enigmatically. Perhaps, but the night belonged to the Scottish National Party.  

Swings of 34%, 35%, 36% to the SNP. In Glasgow North East - which pollsters said would survive for Labour - the swing to the SNP was 39.3%

These figures have never been seen before in general elections in modern times.

It was a dignified exit for the Scottish Labour leader from the constituency, East Renfrewshire, he made his own when he took it from the Conservatives in 1997. Unlike defeated Labour MPs like Michael Connarty in Falkirk he did not blame the voters or say they had been "duped" by a "personality cult".

Jim Murphy says he is staying on as leader. Normally, a party leader defeated on this scale would have resigned forthwith, but he was only elected seven months ago. And the grim reality for Labour is that there is no obvious alternative to Jim Murphy. Neither of the runners up in December convinced the party that they could have done any better.

But what will he lead? An empty shell. The Scottish Labour Party cannot continue in its present form, everyone agrees upon that.

The former First Minister, Henry McLeish told me he believed that there had to be a new federal structure for the UK Labour Party that would allow the SLP to pursue a very different course from the party south of the Border.

Would this mean the Scottish Laboru Party ceasing to be a Unionist party? Henry McLeish doesn't demur. This is year zero for the party.

If Labour is defeated south of the border in the manner forecast by the pollsters, Ed Miliband will not be leader much longer and Labour will possibly be turning to the political right, just as the Scottish party is moving to the left to challenge the SNP.

Is this a one party state as the Liberal Democrat Nicol Stephen called it? No. This result is a product of the perverse first past the post electoral system. This is the other casualty of the night.

The case for electoral reform as well as a federal restructuring of the UK, is now surely unanswerable.

03:00: It isn't a tsunami it is an "extinction level event" according to the former SNP minister Mike Russell. And he may be right.

I have never seen a swing of 35% in any election before. But that was the measure of the SNPs victory over Labour in Glenrothes.

Labour's shadow foreign secretary, Douglas Alexander, not just defeated in Paisley but defeated by 6000 votes. And by a 20 year old Mhairi Black who is still a student. She thanked her mum and dad in a rather gracious acceptance speech.

At 2.53am the SNP took Labour's safest seat of all Kirkcaldy - the seat vacated by Labour former Prime Minister Gordon Brown. Labour hopes now rest on tactical voting Edinburgh South to prevent a clean sweep.

 

01:21: For the SNP the implications of the "tsunami" are also beginning to sink in.

The Nationalists hadn't dared to believe the opinion polls. But now it is becoming a reality and they have to address the political and constitutional implications. 

It could be that there will be no significant unionist voice left in Scotland after tonight.  Can the UK continue in its present form?

The former SNP leader Gordon Wilson was reminding me earlier tonight that only 20 years ago this would have been a mandate for independence under the old party constitution. 

"They may be rather regretting that now" he says with a smile, hastily adding that he is not calling for UDI. 

But some in the party well might.  At the very least it will embolden those on the "45" wing of the movement who want an early referendum. 

 Nicola Sturgeon is still holding the line that there will have to be a "material change" before there can be another ballot on independence.  My own view is that her authority will to so great after this result that she will be able to hold the line against the 45.

 It may be that the ball is now in David Cameron's court.  Will he respond to those on the Conservative benches who would like to see Scotland "given enough rope to hang itself" by fast forwarding fiscal autonomy. 

 

00:42:  As the ballot boxes were opened Labour hearts were broken - and that's a quote from one desolate former MP. It's one thing reading the polls.  Labour were braced for bad news.

But the reality is only now dawning. Glasgow an expected wipe out.  

The SNP taking Dundee, most of Edinburgh.  

Of course it is still too early to confirm that the SNP have over 50 seats. But what we can say is that Scottish politics has changed forever.

Labours half century dominance of electoral politics is finally over. As the Labour MP Ian Davidson might put it. All that's left is to bayonet the wounded.

 

10.24: There are exit polls and there are exit polls. This one is more like a neutron bomb.

It has silenced just about everyone here where I am, in the green room at the BBC's HQ in Pacific Quay.

Politicians and spinners, SNP included, are sucking their teeth and saying: 'No way, jose".

I mean: the SNP taking 58 out of 59 seats? No one believes that.

The Tories with 316 seats and an overall majority? Out of the court, say Tory spinners.

Labour are looking intensely anxious as well they might be because this exit poll indicates that with only 239 seats they have no chance of achieving power in Westminster even with all the small parties and the SNP. Labour are still saying they fully expect double figures in Scotland tonight, and that Ed Miliband can still be PM.

The only people looking glummer than Labour are the Liberal Democrats who are down to 10 MPs in this exit poll.

That's ten in the whole of the UK, not just in Scotland.

Remember, in 2010 the Liberal Democrats won 11 seats in Scotland alone.

The SNP? Well they won only 6 seats only five years ago.

Professor John Curtice who compiled this exit poll is going to have a tense night.