Gordon Brown hopes that constitutional reform will help restore the trust of voters in government as well as pleasing political anoraks.

When he launched his Labour leadership campaign in May he sought to draw a line under the Blair years by claiming he would pursue a new style of government - humbler, with more emphasis on substance than style, a government that would take more notice of Parliament and of public concerns.

His plans for a "different type of politics" have so far been more mood than detail, but he has indicated that an identifiably Brownite package of constitutional reform - with a bill to be introduced in the autumn - will emerge.

Speaking at his campaign launch, he said: "I want to build a shared national consensus for a programme of constitutional reform that strengthens the accountability of all who hold power; that is clear about the rights and responsibilities of being a citizen in Britain today; that defends the Union, that is vigilant about ensuring the hard-won liberties of the individual, for which Britain has for centuries been renowned around the world, are at all times upheld without relenting in our attack on terrorism."

One of the first changes to be mooted was to give MPs the final decision on whether to send the country to war.

It looked possible this could have become a convention after Blair gave the Commons a vote before the Iraq war, and Brown did not specifically commit to a change in legislation.

He told the Telegraph in April: "Now that there has been a vote on these issues so clearly and in such controversial circumstances, I think it is unlikely that except in the most exceptional circumstances a government would choose not to have a vote in Parliament."

Brown's allies were said to have indicated at the time that he might consider ending the royal prerogative, which allows the prime minister to exercise powers without an act of Parliament.

MPs could also be given the power to vet public appointments on the American model, to cut accusations of cronyism.

There has been talk of the need to rebalance power between Parliament and the executive - a response to the perception that Blair's sofa-style of government ignored MPs.

Speaking to Sky News in March, Brown ally Ed Balls said: "We have got to find ways where we make Parliament, the centre of our democracy, more important.

"Partly it is about giving it more power but also let me just say about more statements in Parliament and less announcements on the Today programme."

One idea discussed is to set up a constitutional convention with cross-party involvement, which could enshrine certain rights and responsibilities and lead to a written constitution.

Private discussions between Brown and Liberal Democrat leader Sir Menzies Campbell earlier this month may not just have centred around giving a few Lib Dems frontbench jobs but were also apparently talking about a cross-party constitutional convention.

On electoral reform Brown has said little, but he is known to oppose anything that would break the link between MPs and their constituencies.

This has led some to suggest that while he is opposed to pure proportional representation - and the outcome of the Scottish elections will have done little to endear him to it - he could back the alternative vote system.

This allows voters to list their preferences in order, so that if no candidate wins a majority the second choices of those who picked the least popular candidate are counted.

There is more conjecture than concrete detail about what Brown might have in mind, and his comments have been open to interpretation.

But in the case of Lords reform, where MPs have voted decisively for a fully elected second chamber, he is likely to have to come off the fence sooner rather than later.

In March he voted for an 80 per cent elected chamber, but it has been suggested he is preparing to push a fully-elected chamber, elected by PR, through an unwilling House of Lords.

However this may have to wait until after the next general election, when all three main parties are expected to put the pledge in their manifestos.