AH, Christmas. A time for families to come together as one, for bonds of love to be renewed. Unless you happen to be members of the Labour Party, in which case run as far away from each other as you can. Duck and cover, or just cover yourself with the duvet till the shouting stops. Who knows, you might just survive to see the Spring.

“Fury, despair, misery and denial” was how Margaret Hodge summed up the feelings at this week’s Parliamentary Labour Party post-mortem into the party’s worst General Election defeat since 1935. That was putting it mildly. The extent of the crisis perhaps only became truly clear when Tony Blair took time out from his lucrative retirement to give his tuppenceworth. It is always bad when Tone dares to show his face.

The former Prime Minister, appearing as the artist who won three elections rather than the one who took the country into a disastrous war on a false prospectus, has had his think tank people drill down into the results and come up with a list of lessons Labour must learn.

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This was “no ordinary defeat for Labour” said Mr Blair. Among the reasons for the disastrous outcome were an absence of leadership on Brexit, the adoption of ultra-left policies, a failure to deal with anti-Semitism, and the decision to back an election at a time when the leader was woefully unpopular.

He did not miss and hit the wall. “The result has brought shame on us. We let our country down. To go into an election at any time with such a divergence between party and people is unacceptable. To do it at a time of national crisis when a credible opposition is essential to the national interest is unforgivable.”

Other opinions are available. Those looking for a starting point back to power would do well to listen to former Labour MP Mary Creagh, who lost her Wakefield seat last week.

Ms Creagh’s mix of icy dignity and red hot rage was unleashed on Mr Corbyn when she came across him joking and laughing and taking selfies with youngsters. She was in the Commons to make her staff redundant, and so could be forgiven for being not quite in the festive mood.

She was still furious when she went on Channel 4 News later to recount the clash with the not so dear leader. Her closing remarks contained a very important message, one that every party, indeed many an organisation and business, should have framed and placed on the wall. The Labour Party, said Ms Creagh, “has no God-given right to exist”.

No God-given right to exist. There you have it. In time, this General Election will go down as the false flag poll, with parties posing as something they were not. Conservatives positioning themselves as champions of the working class. The SNP translating votes to stop Boris and Brexit into a push for another independence referendum. Labour presenting itself as a government in waiting when in reality it had long been an electoral disaster waiting to happen. Now Labour, facing the threat that Ms Creagh outlined, has to change, but how?

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As a rare piece of luck would have it, there is guidance close at hand. If Labour wants to swerve oblivion it should look north to what happened to the party in Scotland. Just as Scotland was used as a testing ground for the poll tax, so the country has hosted something of an experiment into what it takes for a mighty electoral force, in power for generations, to be reduced to just one remaining MP.

Think of it as a memo from branch office to HQ.

First, do not forget where you came from. London, and particularly north London, is not the UK. The big cities are not the country as a whole. For too long, Scottish MPs were used as lobby fodder by the Labour leadership in London. There were so many of them a few casualties come election time did not matter. As for calibre of candidate, any chump with a red rosette would do. In modern, social media-dominated politics and journalism, there is no hiding place for the incompetent and lazy.

Second, be distinctive. As the old hymn has it: “Dare to be a Daniel, dare to stand alone, dare to have a purpose firm, dare to make it known.” Do not enter into damaging alliances with other parties who fundamentally do not have your best interests at heart. See the Better Together campaign in the independence referendum, and overtures from the SNP to the London Labour leadership in the 2019 General Election. What did Labour get out of such talk? Nothing.

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Third, stay relevant. Scottish Labour failed to pick up on, then keep pace with, Scotland’s increasing sense of national pride and desire to go its own way. When Labour did wake up to the need for change it drifted between being grudging and resentful or patronising. Come election time, the party that had so long identified with Scotland found Scotland was no longer returning its calls.

Fourth, elect a good leader. It cannot be stressed enough what a disaster Mr Corbyn has been to your continued chances of existence.

Distant, vacillating, stubborn, unable to think on his feet, he was the gift to the opposition that kept on giving. He was also the prisoner of a coterie of hard left ex-public schoolboys, lifelong practitioners of student politics, and union leaders old enough to know better.

Now, it may seem rum for Scotland to advise on Labour leaders. In any sane scenario, the party chief up here would also have quit on losing all but one MP. But take it from Scotland, a country that has watched Labour leaders decline from the sublime to the unfunny ridiculous, finding the right person matters. Be as ruthless as the Tories in picking someone who can win elections. You can be as principled as you like, but if you are not in power nothing can get done.

Fifth, and this is perhaps the toughest goal of all to achieve, be lucky in your competitors, or at least have the means and guts to stand up to them. Scottish Labour has been consistently outperformed by a governing party that has never lost the knack of behaving like an opposition. The SNP has grown fat in power and MSP and MP numbers, but it has stayed hungry for the fight.

Taking on the Tories and their 80-seat majority is not going to be easy. But where there is still life in Labour, there is hope.