Andrew Grice: Brown has been forced to lower expectations

Gordon Brown has softened his language in recent days as he lowered expectations ahead of what might be achieved at next week's G20 London summit.

Ambitious talk of a "Bretton Woods II" agreement and "grand bargain" between the world's 20 richest nations has given way to a more modest assessment of what might be achieved on 2 April. Asked on Monday whether the summit might create a successor to the post-war financial order created at New Hampshire in 1944. Mr Brown replied: "We are involved in a long process. We had a meeting of the G20 in November; we have got a meeting in April, but this will be part of a process."

In Strasbourg on Tuesday, the Prime Minister trumpeted, "the biggest fiscal stimulus the world has ever agreed". His words were meant to chime with President Barack Obama's call for countries to do more to spend their way our of recession. But Mr Brown had to broaden his agenda for the summit after Mervyn King, the Bank of England Governor, declared there was no scope for another big fiscal boost in Britain in next month's Budget. Anxious to play down damaging reports of a split between the Chancellor Alistair Darling and Mr King on the one hand and himself on the other, Mr Brown insisted that fiscal policy was only one instrument, pointing to quantitative easing (in effect, printing money) and interest rate cuts too.

Yesterday, Mr Darling told the Commons that other GO leaders would not be expected to rewrite their budget plans when they arrived in London – playing down the prospect of a co-ordinated fiscal boost being agreed next week. Instead, the 20 leaders are likely to repeat the language agreed by their finance ministers two weeks ago – "to take whatever action is necessary until growth is restored". This compromise would allow Mr Brown to say nations had not ruled out further fiscal action, while more cautious European leaders such as Germany's Angela Merkel could "wait and see" whether existing measures work.

Close allies insist Mr Brown was right to raise the summit's sights and pressure other leaders. He answers critics who accuse him of overhyping by quoting Michelangelo: "It is better to aim too high and fall short than to aim too low and succeed. And that is the choice we face now."

The downside is that commentators may declare next week's summit a flop. The Brown camp is braced for that, saying that the concrete measures to be agreed and the action that follows will matter more than the media's instant verdict.