Sometimes, even in journalism, things happen as a result of intelligent design. Early this year it occurred to me to ask David Cameron’s office for an interview early in July. I chose July on Stanley Baldwin’s view that “July is always a bad month for prime ministers”. It is usually a good month for news; most years have a July crisis.

I called on Mr Cameron in the middle of last week. In the previous ten days Gordon Brown had become Prime Minister, a new Cabinet had been appointed, the Shadow Cabinet had been reshuffled and there had been attempted car bombings in London and at Glasgow airport. Most of the furniture of politics had been rearranged. There was also the heartening news of Alan Johnston’s safe return.

In terms of the domestic agenda, most of the new Conservative policy papers will be coming out later in the summer; tomorrow Iain Duncan Smith’s central policy paper on social breakdown will be published. I spent a good part of the interview discussing the issues of foreign policy and security. One new appointment had been announced that is likely to prove extremely important. Mr Cameron has appointed Dame Pauline Neville-Jones to the Shadow Cabinet. She will be advising him personally on security issues. As it happened, I sat next to her at an embassy lunch a day or two earlier. The feeling of awe and admiration that has always come over me in her presence was fresh in my mind.

On Wednesday I was welcomed by Cameron’s active young office. He himself is an intelligent professional, with the politician’s equivalent of a doctor’s bedside manner. An easy man to talk to, at ease with himself. He is an instinctive moderate, and does not make cheap political points, but discusses each issue on its merits. He is still definitely a young man, as Mr Blair was when he was leader of the Opposition. That must be an electoral advantage.

It has been Mr Cameron’s principle to support the Government when he thinks it is right. He believes that an Opposition that attacks policies it would undoubtedly be introducing if it were in government can only undermine public confidence. He applies this principle particularly to the issues of security; he sees them as issues of national interest that should, as far as possible, “be taken out of politics”.

Interestingly, Mr Brown has appointed two non-party advisers, Admiral Sir Alan West and Lord Stevens of Kirkwhelpington, who will make it easier to maintain a bipartisan security policy on the government side. Dame Pauline, who will be going to the House of Lords, has a mind as decisive as a guillotine, so helping to reach consensus will not involve any weakening of the Opposition’s rigour.

In fact, there is a substantial consensus over the broader range of foreign policy involved in countering the threat of Islamic terror. Mr Cameron discussed Conservative policy towards the Middle East, where he considers that British influence should be used to strengthen European attitudes towards Iran, in terms of the willingness to employ sanctions, but to mitigate US attitudes, to encourage America to offer carrots to Iran as well as carrying a big stick. On Iraq, he supports the Government’s priority of building up the Iraqi army; like the Government, he would continue the existing rundown of British troops in Iraq.

There has been a shift in the balance of influence between the professionals and the politicians because the Foreign Office gave proper warnings of the problems that might arise in Iraq, but Tony Blair effectively overruled them. This has raised the influence of the Foreign Office, both with Mr Brown and with Mr Cameron. The appointment of Dame Pauline is itself a Conservative recognition of the need for professional experience.

However, Mr Cameron is quite clear about the contentious issue of the European constitution. That is an issue on which the Government and the Opposition take opposite views. Mr Cameron considers that Mr Brown has an obligation to fulfil Labour’s promise to hold a referendum before the ratification of the revised treaty. He thinks it is contradictory to promise to consult the people more, and simultaneously to refuse to consult them on Europe. He thinks that the Prime Minister is underestimating the strength of public opinion on this issue.

The Government has created its own problems. It failed to negotiate the original constitutional treaty from the British point of view and it failed again in the negotiation of the reform treaty. British public opinion is in favour of a free-trade Europe and opposed to a single federal state. President Nicolas Sarkozy of France seems now to be against a free-trade Europe but in favour of a federal European state, just as Bismarck himself was in favour of a protectionist federal Germany.

Mr Brown weakly accepted Mr Blair’s decision to go to Brussels by himself, as a lame duck Prime Minister, and agree the revised treaty. The British view has never been put. The only person who has argued it was David Heathcoat-Amory at the original convention before the constitutional treaty. He was good, but an opposition backbencher cannot expect to outweigh both France and Germany.

Mr Cameron is unequivocal in his support for a referendum on any European constitution, which includes the latest treaty. This is important in itself. It is also important politically. Polls suggest that the large majority of British voters are opposed to the creation of a single European federation. That was not what they were promised; it is not what they want. Some polls suggest that more than 90 per cent support a referendum. At an early election Labour would presumably fight on a “no referendum” platform. That must, for them, be a serious objection to any early election.

Times Recommends

• It’s the beginning of the affair
• Afghanistan: still a price worth paying
• Heroes of the downtrodden