Gordon Brown will place 'clear blue water' between himself and Tony Blair when he lays out a vision for Britain - and how it should be governed - which will mark a dramatic departure from Labour's last decade in power.

As the Prime Minister's last band of supporters prepares to rally round the Chancellor, Brown spent the weekend finalising his pitch to the nation in which he will pledge to boost the role of Parliament, downgrade the status of political advisers and acknowledge the public's anger the Iraq war.

With his coronation as Labour leader a certainty after winning the support of Charles Clarke, John Reid and John Hutton, the Chancellor is planning to signal a major break with the Blair era by letting it be known that he has little interest in using Chequers as a weekend retreat for his young family.

Unlike Blair, who spends as many weekends as possible at the Prime Minister's official country residence in the Chilterns, Brown will return home to Scotland on Fridays and will mainly use Chequers for diplomatic meetings and brainstorming sessions with civil servants.

With the move on Chequers designed to show a change in style, Brown will signal a major change in substance by burying one of the most controversial aspects of Blair's 'sofa style' of government and scrapping a special law which gave unprecedented powers to political advisers - most notably the No 10 chief of staff Jonathan Powell and the former press secretary Alastair Campbell - to issue instructions to civil servants.

The move will mark a major breach with Blair who has been dogged by criticism that he politicised Whitehall by giving supporters senior roles normally held by impartial civil servants. The Chancellor is expected to take special advisers with him into No 10 but the traditional demarcation lines separating them from career civil servants will return.

Lord Butler of Brockwell, the former cabinet secretary who approved the change to the Order in Council governing the conduct of special advisers, in 1997 last night welcomed the proposed change. 'I obviously think it is fine,' Butler told The Observer. 'What Gordon Brown means is that he will not have special advisers in these positions, which would be great.'

The two-month Brown coronation will move a step closer today when the Blairite cabinet ministers, Reid and Hutton, follow the example of Clarke and announce they will throw their weight behind the chancellor. The seven-week contest, in which either Michael Meacher or John McDonnell will try to mount a token challenge from the left, is expected to kick off on Thursday when Blair tells the cabinet he will stand down in early July.

Brown will formally announce his bid for the Labour leadership on Friday or Saturday ahead of the opening of nominations on Monday week. At his leadership launch he will say that he has spent most of the past year listening to people's concerns in a series of lengthy consultations. This has convinced him that Labour can retain power at the next general election, but only if it neutralises a series of weak spots to show it understands voters' deep dismay with the party after a decade in power.

When he does outline his plans in detail over the course of the seven-week campaign, he also will attempt to draw a line under sleaze by announcing changes to the way allegations of ministerial wrongdoing are judged.

Brown has held talks with Sir Alistair Graham, the outgoing standards watchdog, and Sir Philip Mawer, the parliamentary standards commissioner, to examine the ministerial code, the rule book for good behaviour.

'This is not about trashing Blair,' one Brownite MP said. 'But it is about setting out a distinctive agenda.'