British Labour Party - will truce prevail?

Britain's faction-racked Labour Party is making a massive effort to end doctrinal warring and achieve unity in time for the next general election.

After more than a year of bickering and bitter public argument between the party's radical left and moderate right, leaders of both sides have promised to show self-restraint and agree to a truce, however uneasy.

Impetus for the fence-mending operation came from the trade unions, the major source of Labour Party funds. After a meeting between Labour's political leadership and heads of major trade unions, the so-called ''darling'' of the left, Tony Benn, let it be known that he would probably not attempt to unseat his right-wing foe, Denis Healey, as deputy leader of the Labour Party.

A battle last year between Benn and Healey for Labour's No. 2 position split the party and heavily reduced its popularity in the country.

After the consultation between party and trade union chieftains, the Labour Party leader, Michael Foot, said he hoped peace had broken out in the Labour movement. He called on Labourites to close ranks and prepare to do battle with the conservative government of Margaret Thatcher.

If the truce holds, it will be purchased at considerable cost to Labour's moderate wing. Mr. Benn has stipulated that there must be no purge of Labour leftists, a measure being urged on Mr. Foot by Healey supporters.

Nor should there be any attempt to undo the gains made by the party's radicals over the past two years. Otherwise, Mr. Benn has privately made it clear that he will reopen the party's wounds and resume his campaign.

Mr. Foot was tempted to accept the Bennites' terms because he knew that continuation of the factional struggle would undermine his own leadership role and probably destroy any chance of the Labour Party regaining enough popularity to be able to challenge the Conservative Party.

Mr. Foot's problems have been compounded by fresh signs of strength by the Social Democratic Party (SDP). A vacancy has arisen in the Scottish parliamentary seat of Hillside in Glasgow, held until now by the Conservatives.

The SDP is expected to put up Roy Jenkins, former deputy leader of the Labour Party, as its candidate. If this happens, Labour will almost certainly take third place.

Mr. Foot will also have to take account of steps by the Conservatives to improve their standing with the electorate. With about two years until the next general election, Mrs. Thatcher has ordered her treasury ministers to reexamine economic strategy.