THE five economic tests are to remain the key factor in determining whether Britain enters the euro after Gordon Brown rules out early membership on June 9, The Times has learnt. It means that the Treasury’s effective veto on the decision will be maintained.

After a week in which Cabinet government has reasserted itself, however, it is becoming clear that Mr Brown’s statement on that day will probably be the most pro-euro ever made by the Government.

Tony Blair almost slipped up at his monthly press conference on Thursday when he came close to saying that he was surprised at how wellinformed the Cabinet had been in their trilateral sessions with him and Mr Brown throughout the week. He had said that privately to them at the Cabinet meeting earlier and aides grimaced because they thought he was about to repeat it, offering up easy fodder for the press, along the lines of: “They are not as thick as I thought they were.”

It is clear, however, that after a lengthy week of reading and consultation on Mr Brown’s 18 technical studies the Cabinet is closer than it thought at the beginning.

There has been movement. Members of the Cabinet now accept that Mr Brown is not anti-euro in principle and he appears to have convinced some that there are circumstances in which he would happily back entry. Mr Brown is also reported to have recognised that the centre of gravity in the Cabinet and parliamentary party is pro-euro, given the right conditions, and responded appropriately.

For their part, ministers appear to have accepted Mr Brown’s verdict that the economics must be paramount because entering in the wrong economic conditions (remember the ERM?) would wreck the political benefits of going in. When trouble erupts, as it did this week when Peter Mandelson suggested that Mr Brown had outmanoeuvred Mr Blair, the five economic tests as the basis for the decision are always used to steady the ship.

Ministers will receive Mr Brown’s assessment of the five tests next week. Mr Blair and Mr Brown have, however, been speaking for weeks about the Commons statement of June 9. They are close to an agreement.

Mr Brown will deliver a “not yet” verdict, saying that although there has been progress the tests have not been passed. He will leave open the door to a further assessment later in the Parliament and, much to the satisfaction of the pro-euro group, he will set out what they will eagerly call a “route map” for euro entry. What that means is that Mr Brown will set out a number of areas, such as bringing the housing market into line with Europe’s through greater use of fixed-term deals and economic reform, on which progress can be judged to decide when a future assessment should be held. He may not himself use the route map description.

The route map will not, as some of the pro-euro group would like, imply a “pre-decision”. In other words it will not, for example, state that Britain will be in the euro by 2007 or 2008. No date will be set for the next assessment and it will be made clear that when one is set the five hurdles will still have to be cleared.

It will, however, leave the strong impression that the objective is to get into the euro. Ministers will also be given rein to make the case for the euro, provided that they always make clear that it can happen only when the economic conditions are right.

Mr Blair and Mr Brown are both reported to feel vindicated by their decision to involve the Cabinet in an elaborate process of consultation. June 9 will be their day as well as Mr Brown’s.

Downing Street believes there will be less “freelancing” by ministers on either wing of the argument in future years, as there was after the euro was ruled out in 1997. That was always seen as a decision made in the Treasury. “They can hardly go around slagging off a decision that they have been part of over a period of weeks,” a senior aide said.

The mood in the Cabinet is good, according to several senior ministers. Officials are keeping their fingers crossed but there has not been a single authoritative leak from ministers of the contents of the 18 euro studies sent to them last Friday. “Ministers know that if the Cabinet is to work properly they cannot go around blabbing about what is going on,” one said yesterday.

They will be tested again next week, probably Wednesday, when the Budget-sized assessment is delivered to them at their homes or wherever they happen to be enjoying their Whitsun break. According to ministers the Cabinet is also a quieter gathering in the absence of Clare Short, who irritated or amused them with her running commentary on subjects well beyond her brief at international development.

It is impossible to disentangle the debate from the succession. Mr Blair denied this week that he had offered to hand over to Mr Brown in return for an easing of his position on the tests. Mr Brown’s aides have denied that he offered a similar deal to Mr Blair, and Mr Brown said on Sunday that he would never bargain when the national economic interest was involved.

Those stories will no more go away, however, than the suspicion among ministers that Mr Brown may be better disposed towards the euro when and if he becomes Prime Minister and leaves the Treasury and that Mr Blair will indeed be relaxed about standing down if and when he has tried to take Britain into the single currency. Win or lose, most ministers think, he would almost certainly go after a referendum in the first 18 months to two years of the next Parliament.

Mr Blair and Mr Brown believe that the euro is the biggest decision of Labour’s second term. In spite of doors being held firmly open, it may yet be the biggest of the third.