What difference would a Brown government make?

What would Gordon Brown do as Prime Minister? It is the biggest unknown in British politics.

Critics claim the inscrutable Mr Brown has deliberately concealed his agenda. Although he has said little about some issues, notably foreign policy, he wants to make maximum impact in his first 100 days if he becomes Prime Minister. But his speeches and statements do provide plenty of clues.

THE BIG BANG?

There are signs that Mr Brown is looking for a landmark announcement like his decision days after the 1997 election to hand control of interest rates to the Bank of England.

It could be a raft of reforms to rebuild the voters' trust in politicians, perhaps through a modern written constitution setting out basic rights and responsibilities for all citizens and the roles of parliament, judiciary and government.

Mr Brown has called for parliament to be given a veto over sending British troops to war. The House of Lords could be reformed, with the 92 remaining hereditary peers removed and at least half of the second chamber being elected by the voters.

To try to draw a line under allegations of "sleaze", an independent watchdog would investigate complaints that ministers have breached their code of conduct. The independence of Whitehall could be safeguarded by a new Civil Service Act and the powers of spin doctors curbed.

Mr Brown may show a surprisingly open mind to reform of the voting system at general elections, possibly by backing the "alternative vote" under which people list candidates in order of preference and the bottom candidate drops out until one has majority support.

PUBLIC SERVICES

Blairites want to test Mr Brown's commitment to extending the Government's reforms to public services, saying more "choice" for consumers and competition between providers is needed to drive up standards.

Mr Brown would continue efficiency reforms but is less convinced of the need for a further injection of market forces which might undermine what he has called "the ethic of service".

To head off the Tory charge that he is a throwback to Old Labour, Mr Brown might demonstrate that he is not in hock to the trade unions by bringing in a reform they oppose, such as breaking up national pay bargaining.

SECURITY

Mr Brown would want to reassure voters that he would not be soft on crime or terrorism. He may attempt to increase from the present 28 days the time for which police can hold suspected terrorists without being charged. Mr Blair's proposed 90-day limit was rejected last year. The Chancellor has already angered left-of-centre MPs by pledging to keep Britain's independent nuclear deterrent.

FOREIGN AFFAIRS

Atlhough an Atlanticist rather than a Europhile by instinct, Mr Brown is expected to drop the "hug them close" strategy under which Mr Blair refuses to differ in public with Washington.

In an attempt to draw a line under the Iraq war, Mr Brown may acknowledge that mistakes were made and will be anxious to ensure British troops return home as soon as possible.