Leading article: The Premier in waiting

Gordon Brown is a leader emerging from the shadows. After Tony Blair's highly personal rebuff in the House of Commons last week, the Prime-Minister-In-Waiting adopts a carefully modulated stance in his interview with our Political Editor today. Mr Brown offers the Prime Minister total but unspecific support. Tony Blair should be supported, he says, without attempting a point-by-point defence of the unsuccessful attempt to extend the limit for detention without trial to 90 days.

It is hard to believe that the Chancellor would have pursued such illiberal populism had he been prime minister. Fortunately, the House of Commons came to the right conclusion last week, thanks to the Conservative Party's recent conversion to the cause of defending civil liberty. This shift in the Tories' position is certainly surprising, and Mr Brown is a little churlish to call it "opportunism". Instead, David Davis, the shadow Home Secretary, should be congratulated for a robust stand on the principles of justice. It is important that David Cameron, if he becomes Tory leader, should hold firm to it.

Mr Brown, meanwhile, is keen to move on to next business. "We were elected on a manifesto and Labour MPs who stood in the election will accept they have a duty to implement that manifesto," he says.

The dilemma of his position is exquisite. He neither wants to work against Mr Blair nor is it in his interest to do so. Yet he has to try to create enough political space to maintain a separate identity, and to allow himself scope to go in new directions when he takes over. If he is silent it could be interpreted as disloyalty rather than discretion; if he speaks, his words risk being over-interpreted for coded messages. He would prefer to take over the top job after a period in which he and Mr Blair are seen to be working in partnership, yet the Prime Minister is unlikely to hand over to him voluntarily until relations with Labour backbenchers have become even bloodier still.

The timing of Mr Blair's departure, therefore, is still largely a matter for Mr Blair. Mr Brown's emphasis on the Labour Party manifesto is a significant prop for the Prime Minister. The reforms of public services - and specifically the attempts to improve secondary schools in deprived areas - have been trailed in the manifesto and should be seen through. Over the next few months Mr Brown would benefit from making this more explicit: those who urge Mr Blair to give way to him soon should not do so on the basis that Mr Brown will keep our deeply unequal and often unsatisfactory school system as it is.

On the other hand, Mr Brown's admission that the Government needs to listen more and engage people more could be seen as an attempt to co-opt the Prime Minister to a way of working that is more open to different voices. It is hard to imagine, for example, a government led by Mr Brown according quite the same reverence to the pronouncements of our police forces or the intelligence services.

All prime ministers hope to leave office at a time of their own choosing. But the walls are already closing fast on Mr Blair, and it will not be long before forward progress becomes too difficult to be worth it. When he spoke after the election of the need for a "stable and orderly transition", he made it sound like a long drawn-out process. It need not be. Mr Brown is ready.