WHAT IS HAROLD WILSON trying to do? Once again he has demonstrated his ability to surprise and, probably, to outwit the motley crew the British call their politicians. He has announced his intention to resign without calling a general election; the first time a Labour Minister has done so.

There are several possibilities for Wilson's sudden, unexpected move:

1) He simply wants to get out of politics before the roof falls in on Britain. His statement that he is resigning because of advanced age, lacks credibility--Wilson is only 60 years old. On the other hand, Wilson entered politics young and has been in the upper echelons of the Labour Party for more than a quarter of a century.

2) Wilson is a don manque. He and his wife have always dreamed of retiring to one of the more luxurious and pretigious college masterships at Oxford or Cambridge. Wilson's chances of receiving such a plum would be immeasurably greater if he resigns and lets his friends into power, rather than if he is forced to seek the groves of academe after a defeat in the general elections has let the Tories into power.

3) Perhaps there are as yet unrevealed scandals about Wilson's private life which he wants to forestall revelation of by resignation. In the last few days Jeremy Thorpe, the man who rebuilt the Liberal party, has been the near-victim of pathological lies by an indigent agricultural worker. Rumors about Wilson's private life and his relation to his private secretary, Marcia Williams (scandalously elevated to the peerage as Lady Faulkender a few years ago) could get nastier. Or there may be things no one has ever mentioned in the press. The surprise resignation of Willy Brandt two years ago, and the recent revelations about President Kennedy's extra-martial affairs, should have taught us never to be surprised about what politicians do in their spare time.

4) The last, and probably the most likely explanation, is that Wilson's move is yet another in a long series of political maneuverings that have made him the least trustworthy leader of the Labour Party since J. Ramsay McDonald.

In the Fall, Wilson announced, like Nixon announcing he had become a Keynesian, that he had seen reason: Britain's economy had deteriorated to the point where it was in the best interests of the working class itself to give it a helping hand instead of destroying it. This policy did not receive much substantial embodiment by the government until Chancellor of the Exchequer Denis Healey's budget proposals. Healey proposed slashing public expenditure on welfare, increasing government aid to industry and restoring economic stimuli to the limping Envlish economy. The Bank of England helpfully underscored the seriousness of the situation last week by allowing the pound sterling to fall below the $2 level for the first time in recorded history.

Yet Healey's budget foundered in Parliament. As Wilson prepared to celebrate his 60th birthday, an unholy alliance of Tories, Celtic fringe nationalists, Ulster Unionists, and extremist left-wing Labourites combined to defeat the measure in the Commons by 28 votes. A defeat on such an important question, while it did not constitutionally require the government to resign, immediately called into question its future existence. Wilson cancelled his birthday party Friday and made the Labour leftists see the light. Although it had to resort to the expedient of bringing in MP's on stretchers, the Wilson government won in a replay of the budget battle and assured its short term survival. In the course of the debate, Healy had morally offended many of the hard core leftists, known as the Tribune group and the incident left Wilson's position shaky.

Perhaps this explains why Wilson decided to play his trump card--his indispensability to the Labour party. Only Wilson can hold together the centrist Labour M.P.s and the radical, trades union-based leftists. Which is what he is trying to prove. No replacement for him is in sight, no one acceptable by both wings of the party (the closest available is Jim Callaghan, the Foreign Secretary). By thus calling the bluff of his party rivals, Wilson will be able to return to office with his power and reputation refurbished. The Labour Party cannot afford to do without Wilson at this point in its history. If he leaves office, it will be because he wanted to.