By Nicholas Jones
What Tony Blair will be unable to prevent as he struggles on in his final months as prime minister will be the almost tribal split which is about to take place within the corridors of power in Whitehall and Westminster.
Blair and Brown's animosity dates back to 1994
Make no mistake about it: the Brownites and the Blairites do think and behave differently when it comes to practical politics.
In many ways they do represent two separate strands of the Labour Party.
And once Gordon Brown and his closest supporters take hold of the levers of power - as is widely expected - there will be significant changes in the way in which the Labour government does business.
In-fighting of the kind we have seen in recent weeks might not always make sense to the public - but to a political anorak like myself there a lots of tell-tale signs which illustrate time after time the deep, divisive split which has existed between Blairites and Brownites.
There is nothing new in this phenomenon.
When Margaret Thatcher was ousted as prime minister in November 1990, all her closest advisers and most of her ministers were bundled out of office along with her.
John Major's election as her successor ushered in a new team and a new era of Conservative government.
But that handover, dramatic thought it was, was swift and almost clinical in comparison with the long, drawn-out political warfare which has continued on and off ever since Mr Blair was elected Labour leader in 1994.
While there has never been a definitive answer over the mystery as to whether there was ever a deal between the two men - that Tony Blair promised to hand over to Gordon Brown - Mr Brown always felt cheated of the leadership and that resentment fuelled a decade of animosity which has split the party and led to emergence of two distinct groups of Labour MPs.
It would wrong to use the labels Old Labour and New Labour but they do give a guide to the differences.
For example Mr Brown and his closest aides and supporters are at ease with trade unionists and can live with the left.
Blairites can barely disguise their contempt for the unions and the many traditions of the labour movement.
So you are unlikely to find the Brownites calling for the party to cuts its link with the unions, a demand which has been made repeatedly by arch-Blairites.
It was largely because he pulled away from the unions and tried to find new sources of money for the Labour Party, that Mr Blair found himself entangled in the row over cash for peerages and a Police investigation.
Just as sharp is the divide over the use of spin doctors such as Peter Mandelson and Alastair Campbell.
Brownites have detested the reliance which Mr Blair has placed on the black arts of media manipulation.
They have hated the leaking and briefing against colleagues which Downing Street endorsed and which became so commonplace in recent years.
Mr Brown cannot forgive or forget the way Mr Mandelson secretly briefed for Mr Blair in the 1994 leadership contest.
When he discovered that a politician who he thought was his friend had been working for his rival under the codename Bobby, Mr Brown was incandescent with rage.
And it is alleged subterfuge like that which has fuelled the animosity that in later years became all too apparent.
What we have seen in recent days is merely a curtain-raiser for the political blood-letting which will inevitably take place.
Prime Minister Brown would dismantle Mr Blair's spin machine.
He has promised to restore the authority of the civil service in the hope that he can rebuild public trust in the Labour government.
Secret loans from a coterie of rich entrepreneurs are likely to be a thing of the past.
Mr Brown is thought likely to favour a new and more transparent way of funding party politics.
While it might not be possible to discern much change in the day to day business of government, Mr Brown is likely to give the highest priority to the task of reviving his party.
He has indicated he will seek to improve consultation with Labour's constituency parties and deepen the sense of participation.
Unless he can halt the haemorrhage of party members and unless he can heal the divisions within the labour and trade union movement, Mr Brown knows he could well face the same fate as James Callaghan.
He took over the Premiership from Harold Wilson in 1976 but lost power in the 1979 general election.
What has fuelled the Brownite push against Mr Blair is their fear that history might repeat itself.