THE WORLD FROM...London

PRIME Minister John Major, reelected on April 9 with a solid majority, feels confident enough to adopt revised tactics in negotiating with Britain's European Community partners. Already the new diplomatic style is making London less isolated in dealing with its Continental neighbors.

Instead of the "absolutely not" approach of his predecessor, Margaret Thatcher, when faced with an unwelcome EC demand, Mr. Major is ready with a "yes, but ..." response.

Last week he sent Gillian Shephard, his employment secretary, to Luxembourg with instructions to hew to the new line in a discussion about the length of the working week in EC countries. She discovered that by appearing firm but flexible, she could gain goodwill and room to maneuver.

Mrs. Shephard's task at the outset appeared formidable. The European Commission had proposed that all member countries should limit the working week to 48 hours and that Sunday should be a day of rest throughout the EC. More than 2.5 million British workers exceed the suggested 48-hour limit, and many regularly work Sundays.

Most EC governments support the Brussels proposals, but Major has said acceptance of them would cost British industry 5 billion pounds ($8.8 billion) a year.

Shephard went to a ministerial meeting in Luxembourg April 30 in what a British official called "a mood to get her way and protect our interests."

If she had been representing Mrs. Thatcher she probably would have told Britain's partners that the commission proposals were utterly unacceptable. Instead, after patiently explaining the difficulties posed to Britain by the directive, Shephard said she accepted the principle behind it but wanted the EC to consider "a range of exceptions" to meet Britain's special needs.

She returned to London having secured a six-week delay on a vote on the directive. A Whitehall source said Shephard was confident Britain would be able to deflect the worst effects of the Brussels plan. The source added that, if Britain's partners proved "difficult" at the next meeting, in June, they would be made "gently aware" that London intended to take the matter to the European Court.

Major first used the "yes, but ..." approach at last December's EC summit in Maastricht when he supported plans for closer European integration but refused to endorse a Brussels call for a single EC currency.

At Maastricht Major gave strong support to Germany on the principle of integration. In Luxembourg, Shephard was able to draw on the credit her prime minister had earned at the summit five months earlier. It was with support from the Bonn government that she averted an instant vote on working hours.

By making it plain that the aggressive Thatcher style is a thing of the past, Major is doing more than pile up points in Brussels. He is improving the prospect of the British Parliament later this year ratifying the results of the Maastricht summit.

Explaining the thinking behind the "yes, but ..." negotiating style, a senior British diplomat said it cut both ways to Major's advantage.

"If he works within the spirit of EC unity, he pleases the other Europeans. By insisting on exceptions to meet Britain's needs, he weakens the case of people in his own party who think Brussels is automatically bad for Britain," the diplomat said. "Mrs. Thatcher's obduracy had the negative effect of gaining us enemies in Europe and stiffening the resolve of anti-Europeans at Westminster."