There were 27 leaders having their say as the EU struggled to reach agreement on an “amending” treaty yesterday. But a 28th leading politician had as much input as – and probably more than – the rest.

Gordon Brown, two days from his coronation as the Labour leader, was the ghost at the dinner table on Thursday night and the spectre at the feast at lunchtime yesterday.

He has been talking for weeks with Tony Blair about how the outgoing Prime Minister should handle the negotiations. In mid-afternoon yesterday Mr Blair experienced the weight of the “big clunking fist” on his shoulder.

Their aim was the same: to win an agreement that Mr Brown could present as requiring no referendum in Britain. He knew that he would lose such a vote and did not want such a massive reverse on his early record as prime minister.

His two big demands as the summit entered its second day yesterday were watertight language making it beyond doubt that the Charter of Fundamental Rights would not apply in Britain, and that the the proposed European foreign representative would impinge in no way on the role of the British Foreign Secretary.

The Times understands that the Chancellor worked late with Lord Goldsmith, the Attorney-General, on a legal formula for the charter opt-out, and discussed it with Mr Blair’s negotiating delegation. Mr Blair and Mr Brown had a lengthy conversation before the Prime Minister met any other leaders yesterday, and Mr Blair agreed to push the new wording in the talks.

Mr Brown also had his own “eyes and ears” in Brussels. Jon Cunliffe, who is to be his chief adviser on Europe in Downing Street, was at the summit, with two other Treasury officials. Mr Cunliffe is a tough negotiator who knows Mr Brown’s mind as well as anyone.

He was at the summit in December 2005 that fixed the EU budget. But those were not the days of the stable and orderly transition that has finally been taking place these past few weeks, and Mr Cunliffe was not in the room that day when the final decision to accept a deal that would involve Britain paying more to the budget was taken. Mr Blair, it emerged later, was upset that Mr Brown had become involved in the budget negotiations only at a late stage and felt no obligation to keep Mr Cunliffe informed.

This time he was fully involved. But there was doubt in the British camp last night over whether he had been aware that No 10 was to organise a briefing for journalists showing understanding for President Sarkozy’s position on competition.

Certainly Mr Brown and his team in London were horrified when the lunchtime broadcasters led bulletins declaring that Britain had caved in to the French leader’s demands to win a deal on the treaty.

The Treasury lawyers got to work and concluded that there was scope for confusion over the differing interpretations in the preamble of the treaty and within the main text about the desirability or otherwise of “undistorted competition”.

Mr Brown rang Mr Blair about 3pm London time, told him the draft was unacceptable and suggested changes that could be made to clear up the contradictions between the preamble and the treaty, he hoped without upsetting Mr Sarkozy.

There were discussions with Mr Sarkozy and the result was the announcement of an agreement to end the row. There will be arguments over how influential Mr Brown’s intervention was. But there is no doubt that he hardened Mr Blair’s resolve.

Main issues

— Voting weights Poland bitterly objected to the redistribution of votes for member states because it received half the strength of Germany, based on population size. Even though it was isolated, the strength of its opposition meant that different compromise formulas were offered throughout the day

Status Still a sticking point

— Competition President Sarkozy pushed for the removal of a phrase in the objectives of the EU ensuring that the single market was committed to undistorted competition. The issue flared up late and was reluctantly accepted to help Mr Sarkozy sell the new treaty to French voters while denying them a referendum

Status Agreed upon then fudged. More legal arguments to follow

— Red Card A plan to let national parliaments show EU proposals a “red card”. If enough countries object then the proposals would sent back for reconsideration. The “red card” is designed to help the Dutch Government to avoid a second referendum

Status A compromise offer is likely

— Qualified majority voting A further 51 policy areas will move to qualified majority voting, making them immune from a national veto. Britain and Ireland have argued for opt-outs in the areas of justice, home affairs and social security, one of Britain’s red lines

Status Heading for agreement on Britain’s terms

— Charter on Fundamental Rights Turned from a declaration on a wide range of new rights made in 2000 to a legally binding document. Britain was a lone objector to the scope of the charter because of its potential to be used to challenge employment and social law, including overturning trade-union legislation

Status Britain struggling to get an opt-out that is legally watertight

— Enlargement Several countries pushed for the inclusion of clear legal criteria setting out the rules for countries that want to join the EU. Known as the Copenhagen Criteria, these rules could leave decisions on whether a country qualifies open to legal challenge. Important for the Netherlands in fending off calls for a referendum. Seen as a threat to future Turkish membership

Status Quietly dropped with assurances that the issue will return next year

Times Recommends

• The bright side of this winter rain
• Story behind the picture: Snow Leopard, 2008
• Times Charity Appeal: The Place2Be