As Gordon Brown stands up to deliver his Pre-Budget Report today, the Prime Minister will be right beside him, technically at least: the two men sit shoulder to shoulder on the Commons green benches. But their proximity will carry little metaphorical weight. For trust between Nos 10 and 11 Downing Street approaches vanishing point. Another round of public disharmony is being inflicted on a distinctly weary public.

In Tony Blair’s eyes, Mr Brown seems more interested in winning the Labour leadership than the general election or the EU referendum. As The Times revealed yesterday, a book to be published early next year — Brown’s Britain by Robert Peston — will set out Mr Brown’s stall of policies. Just as a general election is imminent, the Chancellor will be trying to distance himself from the Prime Minister in the eyes of the party members, MPs and trade unionists who make up Labour’s electoral college.

Mr Brown has apparently calculated that he owes relatively little to Mr Blair. The occupant of No 10 has let him down so many times, by refusing to hand over the leadership, that the Chancellor has become more than usually impatient. The appointment of his rival, Alan Milburn, to oversee election campaigning, and Mr Blair’s undertaking to serve a full third term, were serious setbacks in an already troubled relationship.

Mr Brown’s disgruntlement is understandable. But he is not a wholly innocent victim. Mr Blair, for his part, has found his Chancellor notably unsupportive during a few awkward moments. Mr Brown has also been unhelpfully secretive, sometimes refusing to divulge to the Prime Minister, who is after all First Lord of the Treasury, his Budget proposals. The differences between them are magnified by those around them — because of their lack of communication, these aides are taken as accurate spokespeople when their opinions are often just their opinions.

On Europe, the Chancellor is much more in tune with the wider electorate than is the Prime Minister. Had Britain joined the euro in this Parliament, as Mr Blair would have had happen,the country would by now be suffering the consequences. Instead, the Bank of England has been able to maximise growth by setting interest rates appropriate to Britain’s own circumstances.

But the Chancellor would do better to concentrate on the nation’s burgeoning budget deficit than on his burning ambition to be Prime Minister. He does not need to sell himself to the Labour Party, but does need to articulate clearly what he means by “enterprise” and to consider more seriously the stifling impact of over-regulation of business.

Voters will have genuine choice at the next election, and divided parties are punished at the hustings. If Mr Brown wants to inherit the leadership and win a subsequent election, he has an interest in the parliamentary majority achieved by the Labour Party being as large as possible. Whether any such landslide is in the country’s interest remains to be seen.