Mrs. Thatcher's election gambit

In calling a general election for June 9, British Prime Minister Margaret Thatcher has again demonstrated the dogged determination and resolve that have characterized her political tenure since taking office in 1979. The immediate question - and one that will be shortly answered by the British electorate - is whether Britain's Iron Lady, as she is called, is on target in her timing, for nearly a year remained before the election needed to be held.

Indeed Mrs. Thatcher herself had favored holding the contest later this fall - or even next year. But her advisers prevailed upon her to seize the moment - when she enjoys strong popular support - and prevent the opposition Labour Party from pulling itself together after the many ideological divisions of recent months.

So the decision can be taken as a logical political move. Labour leader Michael Foot was quick to argue that Mrs. Thatcher's policies have created an ''economic catastrophe of the first order'' and that she was ''pushed, pulled and panicked'' into announcing an early contest. Shirley Williams, president of the opposition Social Democrats, said that the June date was a ''cut-and-run election'' designed to minimize future bad economic news. Still, Mrs. Thatcher would have to be judged the early favorite.

The contest involves unusually sharp choices for British voters between a Labour Party under Mr. Foot that has drifted far to the left of the more centrist policies of former Labourite Prime Minister James Callaghan and a Conservative Party under Mrs. Thatcher that has been far more ideologically conservative than under Prime Minister Edward Heath in the 1970s. The lines are sharply drawn. Labour is opposed to cruise missile deployment, supports cancelling a planned purchase of Trident submarine missiles from the US, and favors removing American military bases in Europe - in each case taking a position diametrically opposite to that of the Conservatives. But despite divergent foreign policy issues, it is the economy - particularly the unemployment question - that will likely be the central concern of voters.

Part of Mrs. Thatcher's rationale for holding an early election no doubt stems from the fact that the British economy is showing a number of signs of recovery from what has been the most difficult recession in postwar history. Inflation is down sharply. Interest rates are falling. But at the same time voters will want to know what a second Thatcher government would do to reduce unemployment currently standing at 3 million persons - twice the level it was when Mrs. Thatcher took office. Is Mrs. Thatcher's stay-the-course approach enough to resolve unemployment? Or would Britain be better off with stepped-up public spending and an incomes policy, as advocated by Labour?

The wild card in the election, as both Conservative and Labour officials are keenly aware, is the newly established centrist Alliance, made up of the Social Democrats and the Liberal Party. In recent weeks the Alliance has slumped somewhat in national standings, suggesting that it will be difficult to gain enough seats in the House of Commons to hold the balance of power in any future government with Labour.

The British campaigners are off and running. It will be a short contest - but not unlively.