At least three uniformed policemen were seen on duty today for the first time since Kampala's capture last week, but a downtown building burned out of control because no one could find enough firemen to extinguish the fire.

On the Easter Monday holiday that mixture of timid goodwill and still inadequate performance symbolized the problems of the provisional government trying to overcome ousted president Idi Amin's poisoned legacy of eight years of rule by terror.

Awaiting Tuesday and the end of the holiday period befor etesting a general back-to-work order, Ugandans lived in suspended animation.

A power failure cut communications with the outside world for 48 hours and stopped Army units that had been fighting for Amin from surrendering by telephone, according to military officials.

But there were some efforts to bring order to this city.

The corpses have been cleared from the streets.

Tanzanian senior officers reportedly were trying to discipline their troops who recently have taken to "liberating" wristwatches from Ugandan civilians and emptying the remaining reserves of whisky, cognac, wine and gin. Tanzania supplied the bulk of the forces that ousted Amin.

Other good news was in the air.

The provisional government was reported convinced that Amin had fled to Libya late last week after his personal aircraft made a refueling stop in the Kenyan capital of Nairobi while he stayed aboard.

The fact that the new government thought Amin was out of the country was tremendously important in terms of its self-confidence and of possible recognition by foreign governments.

Richard Posnett, and old Uganda hand sent back by Britain to assess the situation and very probably recommend reestablishing relations, was welcomed back with bear hugs by old friends in the government he'd known in 23 years in the colonial service before he left in the mid-60s.

Never mind that the adviser to British Foreign Secretary David Owen had to wait three hours for a car at Entebbe Airport to drive him to Kampala or that the government kept him waiting this morning after promising him an escort to help him reopen the British High Commission, closed since 1976.

When this afternoon Posnett Finally managed to open the commission's back door-the front door key brought from London did not fit-he found deep dust, a tea cup, and Bougainvillea advancing down the top floor corridoors-but no Union Jack.

[The State Department said Monday that a mission would be sent to Kamapala soon to discuss reestablishment of relations with Uganda. The U.S. Embassy in Kampala was closed in 1973.]

Never mind that Yusufu Lule, the provisional government's president, was reported very ill after having missed several functions including the Easter mass of rejoicing celebrated in the Roman Catholic cathedral by Cardinal Emmanuei Nsubuga.

The cardinal and archbishop used the occasion to pour his scorn on looters who have gutted Kampala homes and offices and told the faithful, which included two Cabinet ministers and top military officers that a government incapable of protecting property was no government at all.

The most prominent looting victim was a branch of Barclay's Bank of Britain. David Brooks, the managing director for Uganda, estimated that $300,000 in Ugandan shillings was stolen when raiders blasted away a two foot reinforced concrete wall and blew out the steel door.

On Sunday the grisly headquarters of the State Research Bureau, Amin's dreaded secret police, became something of a tourist stop.

The bodies of prisoners murdered by the guards just before their flight early last week have been removed. Everything of value has been carted off by looters.

Yet there is much that remains. There are brochures petronic bugs and computer banks. There are brochures peddling exploding cigarette lighters, remote-control detonators and training "in the art and tradecraft of intelligence, sabotage and espionage."

An address book containing the telephone numbers of key officials carries the warning on its cover: "Bound in poisonous insecticide." Presumably this was intended to dissuade the curious.

A senior civil servant in his Easter best guided a tour of 40 elegant churchgoers and recalled how he was arrested here two years ago at the same time as the late Anglican archbishop Janani Luwum.

The archbishop was made to strip, badly beaten, told to dress again and then taken out and shot, the civil servant said. He himself was saved. He had been arrested along with his minister, who was imprisoned and killed at the same time as Luwum. Both minister and archbishop were said by Amin to have been killed in a car accident.

A Westerner living nearby recalled that that was the worst period, when he could clearly hear the prisoners' screaming far into the night.

In special storerooms lie hundreds of pairs of army boots and dozens of red-trimmed military police caps.

Their owners have fled the scene of their crimes-and the classroom where they were learning how to add 1 plus 1, 3 plus 5 and how to spell "basin" and "door," according to lessons left on the blackboard.