A staged show of Cabinet unity behind Gordon Brown today was undermined by a lukewarm endorsement from potential rival David Miliband.

The Prime Minister took his senior ministers to Birmingham for what was dismissed by the Tories as a publicity gimmick.

It was the first time the Cabinet had met formally outside London since the days of Lloyd George nearly 90 years ago.

Happy days: Gordon Brown chats to Justice Secretary Jack Straw before today's Cabinet meeting

Support: Foreign Secretary David Miliband listens to a colleague during the historic meeting

The high-profile event came as Mr Brown told his party he was ready to 'confront' those who might try to oust him, as he rejected calls for him to go voluntarily.

The Foreign Secretary, who caused a storm this summer by signalling his ambition to lead the party, joined a queue of ministers who stepped forward to back Mr Brown's leadership.

But he left a question mark over the depth of his support by appearing to criticise his leader's performance in his first year.

The Foreign Secretary said Mr Brown was displaying 'more vigour and determination' than before, and would 'prove people wrong' by winning the next general election.

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Factory visit: Prime Minister Gordon Brown (centre) at Jaguar's Castle Bromwich plant in Birmingham with Chancellor Alistair Darling

'I think Gordon is leading us with more vigour and determination and will prove people wrong,' he said. The use of the word 'more' left some listeners to interpret this as Mr Miliband criticising the Prime Minister's previous levels of determination.

Mr Miliband added: 'I am absolutely convinced that Gordon can lead us to victory. He has enormous values, drive and vision and I think we are going to prove people wrong.'

Friends said Mr Miliband was not trying to qualify his remarks when he said Mr Brown 'can' lead Labour to a fourth term.

But with MPs on the lookout for any sign that Cabinet ministers might be considering Mr Brown's future, his words were studied closely.

Gordon Brown arriving in Birmingham where he appeared to liken his resolve to Andy Murray's determination to beat Rafael Nadal in the U.S. Open

Mr Brown set the tone by issuing a rallying cry to ministers. He said he would use his experience of personal challenges to guide his party and the country through the current economic turmoil.

He said Britain was living through a period of 'astonishing change' and claimed that the UK could benefit over the next 20 years despite the credit crunch, climate change and an ageing population.

'We can do well indeed, but we have got to work out together how we can make our way in what is a new world of new change,' he said.

Justice Secretary Jack Straw and Home Secretary Jacqui Smith on a visit to see ex-offenders doing their community service before today's summit

Windswept: Housing Minister Caroline Flint

Before the Cabinet meeting, Mr Brown and his ministers took part in discussions with about 200 representatives of business, the public sector, charities and the media in Birmingham's International Convention Centre.

Every member of the Cabinet has also carried out visits in the West Midlands, themed around issues including community policing, manufacturing, health, jobs and skills.

Downing Street confirmed the event was being treated as Government business, with the taxpayer footing the cost.

But there was a political motive behind the move, because the West Midlands is a vital electoral battleground and the Tories are holding their annual conference in Birmingham in three weeks.

The 'majority' of ministers travelled by public transport, and a minimal number of officials accompanied them, a spokesman for the PM said.

On the train back to London Mr Brown and his team found himself travelling in the adjoining carriage to David Cameron, who was in Birmingham filming with the BBC.

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Game for a laugh: The Prime Minister shares a joke with Jack Straw