John Rentoul: Mandelson shock – there's no hidden agenda

The Business Secretary, irritated by sentimentality over Royal Mail, will push ahead because he thinks he is doing the right thing

Not for the first time the nation asks: What is Peter Mandelson up to? Why is he trying to privatise the Royal Mail, a policy that is unpopular (intensely) with his own party and (less intensely) with the voters, with whom his party has an unavoidable rendezvous in the next 15 months?

Which goes to show only that we are all commentators now. Rather than debate the merits of the proposal, we behave like journalists and ask why it is being proposed. That is an approach that is sometimes justified, but not in this case. The simple answer is that Lord Mandelson is doing what he thinks is right.

I know it has been fashionable in recent years, especially since Iraq, to assume that if a politician takes a decision with which you disagree it is because he or she has an ulterior motive. But surely the very difficulty of providing a credible secret motive in Lord Mandelson's case should be a clue here.

Does he want to cause trouble for the Prime Minister, who brought him back from his Siberian power station? I do not believe that he does. Does he want to do a Blairite yah-boo just to wind up the Triassic Tendency of his party? I do not think so.

He takes the view, and he knows about it from his previous stint at Trade and Industry, that the Royal Mail would benefit from private sector management and private investment. Yet this is a case that has hardly been argued on its merits.

Partly, this is a problem of his own history, not just of his reputation as a Labour rightwinger and media fixer but of his troubled relationship with Gordon Brown. When Brown brought him back to the Cabinet four months ago, it was a shock that prompted mixed reviews. On balance, the idea that it was a brilliant chess move held more sway than comparing it to getting back with a sixth-form boyfriend on Friends Reunited. It reinforced the "experienced team" message – both the experienced and the team, by visibly healing the rift in Labour's family.

As the banking crisis has unfolded, Mandelson has largely stayed out of it. Meanwhile, his tendency to theatricality has enlivened a recent series of leaks of detailed Cabinet discussions – leaks that make Jack Straw's ban on the publication of the bland official minutes from six years ago seem particularly pointless.

At the meeting on 13 January, which approved the third runway for Heathrow, for example, it was reported that Harriet Harman expressed her reservations and said: "I realise the point I am making is irrational." It was at this point that Mandelson's head hit the Cabinet table in mock despair. Not something that Gus O'Donnell, the Cabinet Secretary, would ever put in a minute. Mandelson clashed with Harman again at Cabinet on 15 February, when she reprised her bash-a-banker speech and he warned against looking as if the Government were being blown about by the wind of media furies.

Rather neatly, both leaks illuminate Mandelson's approach to the Royal Mail furore. First, he feels that he is up against irrational opposition. Second, he thinks that leaders should stand firm. Where Margaret Thatcher sensed that some irrational views were shared by the public – she did not want to privatise something with the word "royal" in it – Mandelson thinks that he can do better.

He also has a low tolerance for some "irrational" attitudes to foreigners. Because outside money and expertise is most likely to come from the Dutch or the Germans, patriotism has become the last refuge of the Bill's opponents. Mandelson told Labour MPs who demanded to know why he had to go abroad: "We have looked for management but there must be something lacking in the gene pool of British management."

Proof, if any were needed, that Mandelson lacks something in the soft arts of persuasion. People find this hard to believe because of his reputation as an arch manipulator of the media, but that is not the same as the skill of managing internal coalitions.

The absence of that skill is compounded by his insistence on the need for ministers, and prime ministers especially, to appear "strong" – a word that occurs again and again in Alastair Campbell's diaries. That was partly what Heathrow was about.

I thought the Heathrow decision was wrong, while privatising the Royal Mail is right, but in both cases it is the standing firm that incurs a political cost. Brown got away with the third runway because the voters are conflicted, green issues don't hit Labour's soul and it is never going to happen. Yesterday's attempt by the Daily Mail to suggest that Mandelson supported it only because a friend runs public relations for the airport company BAA was notably feeble.

But the Royal Mail is different, and Brown could still find some device for abandoning the plan. He may say, for example, that the economic crisis makes it a bit awkward and postpone it for, oh, 15 months.

Or he may decide, as Mandelson evidently has, that they might as well do the right thing, because they can. The Conservatives will vote for the Bill, so it doesn't matter, arithmetically, how many Labour MPs rebel. It matters greatly, however, to the party's confidence. Labour MPs hated it when Tony Blair relied on Tory votes to get the Schools Bill through. And it matters for the party's image of disunity. Nick Brown, the Labour chief whip, seems to be encouraging the rebels. At the least, he is showing them unprecedented indulgence, allowing several Parliamentary Private Secretaries (unpaid ministerial aides) to sign the rebel motion.

If Labour MPs did decide that a new leader might save their seats, and looked for an excuse to make the change, it may become relevant that one candidate has been reported as sceptical about the Royal Mail sell-off – and he is a former postman.

But I suspect that we have got beyond such calculations now. Labour is heading for defeat. Yesterday Gordon Brown sounded moderately defiant. "I ask you to consider," he told Labour's policy forum. He and Mandelson will press on, against the party, because they think it is right.