Gordon Brown was hailed as Europe’s new star pupil last night for securing ratification of the Lisbon treaty as the Irish were set a four-month deadline to devise a plan to save it.

As the treaty gained Royal Assent, the Prime Minister shed his low European profile to give heart to EU leaders gathered in Brussels that their cherished document was still alive despite the dramatic rejection in the Irish referendum.

While President Sarkozy led the EU’s top brass in lauding Mr Brown’s “political courage”, Brian Cowen, the Irish Prime Minister, was met with forced smiles at his first summit dinner and asked to explain to the 26 leaders why the Irish people voted “no”.

Mr Cowen barely had time to start his Slovenian-style trout before being asked to give some idea as to what the EU could do for the Irish Republic to produce a “yes”. He pleaded for more time to analyse the results but insisted that the lost referendum should not stop other countries ratifying.

Mr Cowen pledged to come back to their next meeting in October to tell them if he thought that a second referendum could succeed, and what his Government would need from the EU to run a successful campaign.

Behind the expressions of solidarity and “respect” for the Irish vote, however, there was barely disguised pressure on Mr Cowen to plan a second referendum.

Attitudes around the EU table hardened during the day, with Angela Merkel, the German Chancellor, urging a quick decision on reviving the treaty, while others, including José Manuel Barroso, the European Commission President, talked openly of the Irish “problem”. President Sarkozy said the Irish “no” had put the further enlargement of the EU in peril.

Mr Brown’s journey from European zero to hero was heralded with lavish words of gratitude from Mr Sarkozy, who will take over the EU presidency next month and needed British ratification to help him to pick up the pieces of the treaty. “I want to say how pleased I am . . . and thank him for demonstrating political courage by leading the ratification process of the Lisbon treaty,” Mr Sarkozy said after a working lunch with Mr Brown in Paris. “He did this with much commitment and much strength.”

Mr Barroso joined the chorus of praise for Mr Brown, declaring: “I would like to thank the Government and Parliament for the constant support for the new treaty during the negotiation and ratification process.”

In a clear sign that British ratification was being used to pile pressure on Dublin, he added: “The treaty of Lisbon has now been approved by 19 member states. I call on all of those that have not ratified the treaty to continue the ratification process.”

Hans-Gert Pöttering, President of the European Parliament, said: “This shows that the Lisbon treaty is very much alive.”

Janez Jansa, the Slovenian Prime Minister, who is chairing the summit, said that British ratification “proves that it is still a living document”. Most EU leaders are keen to save Lisbon because they have already spent eight years trying to frame a treaty that streamlines the EU machine, reducing national vetoes, creating a president of the European Council and slimming down the European Commission.

Mrs Merkel, seen as one of the architects of the treaty, showed her impatience with the Irish during a debate in the German parliament before the summit. “The European Council must take a decision as quickly as possible. Europe cannot afford any pause for reflection,” she said.

The British were keen to play down their role in applying pressure to Mr Cowen yesterday, with David Miliband, the Foreign Secretary, quick to contradict Mrs Merkel and declare that a reflection period was precisely what Europe and the Irish needed.

“It is premature to talk about deadlines but I think that the Irish Government have made clear they want some time to think about their next moves and if that takes us into the autumn then so be it,” he said.

Extra pressure on the Irish came from senior European figures. Valéry Giscard d’Estaing, the former President of France, who led the writing of the failed EU constitution, said: “The Irish have a right to say no. But a country that represents 0.7 per cent of the European population cannot decide for the others.”

Silvio Berlusconi, the recently re-elected Italian Prime Minister, added to the tension with a remark that EU leaders had less personality than those attending summits when he was last in office. Contrasting the EU of Tony Blair and Jacques Chirac he said: “I see a Europe which has gone backwards compared with two years ago.”

The British attempt to rally around the Irish was undermined by Peter Mandelson, Britain’s EU Trade Commissioner, who was sharply critical of Mr Cowen’s efforts to sell the Lisbon treaty. “An appalling number of rumours, on which people’s prejudices and fears were built” had contributed to the “no” vote in Ireland, he said.

Times Recommends

• Please help: maimed children of war want their lives back
• Cabal seizes diamond riches to buy power
• White House gatecrashers got to the president