Jack Warner dealt a massive blow to England's hopes last month when he dismissed the bid team as "lightweights" and warned they were falling behind rivals like Spain in the race to host the tournament.

But during talks today with Mr Brown in Trinidad, he struck a more positive tone, recognising that England had sufficient sporting infrastructure to host the World Cup tomorrow if necessary.

Trinidadian Mr Warner is also president of the Concacaf union of North American and Caribbean football associations, which controls three of the 24 votes on Fifa's executive committee when it chooses the 2018 venue in December next year.

His support would be crucial for England to host the world's biggest footballing event for the first time since 1966.

In today's meeting - characterised by Downing Street as "very positive and friendly" - Mr Brown stressed the passion felt in England for its national sport, and pointed out that it was half a century since the World Cup was last held in the country which invented football.

He said the Government was completely committed to the bid and that he was personally ready to do "whatever is necessary" to support it. The Government has already offered guarantees of £350million to underwrite the bid.

Downing Street sources said that Mr Warner was very complimentary about England's football stadiums and infrastructure, and recognised that the country was ready to hold the World Cup tomorrow.

Warner did not repeat his previous concerns about the leadership of the England bid, headed by Labour peer Lord Triesman, and the issue of the governance of the did not arise.

In a possible response to Mr Warner's earlier criticisms of Lord Triesman's team, who he said last month should be using personalities like the Queen and David Beckham to win support for England's case, Mr Brown said he wanted to see the best ambassadors for football involved in the bid.

Mr Brown and Mr Warner also exchanged personal footballing reminiscences as they met at the British High Commission in Trinidad & Tobago's capital Port of Spain.

The Prime Minister said that Trinidadian player Marvin Andrews had become "a very good friend of mine" since playing for his beloved Raith Rovers.

And Mr Warner joked that the Premiership had become a "training ground" for the Trinidad & Tobago national team, giving stars like Sunderland's Kenwyne Jones a chance to play alongside world-class footballers.

Downing Street said that Mr Warner had stressed the cultural importance of football, and praised the diversity of the Premiership, which brings together players from all over the world.

A Number 10 spokesman said: "The PM and Jack Warner had a very positive meeting.

"Mr Warner was complimentary about the UK's sporting infrastructure and said he recognised that England would be ready to hold the World Cup 'tomorrow'.

"The PM emphasised his personal passion, and the nation's passion for football and sports more generally. He said the Government was committed to increasing its support for sport, for example by raising the number of hours of sport in schools from two hours a week now to five by 2012."