"If the British Empire was ever like this, there would have been no need for decolonization," a cynic said when questioned the other day about how Britain is running its new-found, but temporary colony of Rhodesia.

Slightly over a month in office and about one third the way through his tenure, Lord Soames, the British governor, is apparently following the philosophy that the least government is the best government.

Privately, the British admit that the policy of leaving practically all the trappings of the white-influenced Zimbabwe-Rhodesian government intact is designed to reassure the 220,000 white minority and keep them in line during the traumatic changes they are likely to face with the installation of a true black-majority government in two months.

Increasingly, the Patriotic Front guerrillas, who fought a seven-year war for power and their supporters are complaining that the British policy is favoring the former government of Bishop Abel Muzorewa, who was elected prime minister last year after negotiating a constitution with the whites allowing them to maintain significant control.

Muzorewa and some whites, however, are also critical of Soames' administration, especially over what they see as lenient treatment of the guerrillas, which thus leads the British to argue they must be doing something right if the opposing sides both find fault with the government.

It is reminiscent of the 15-week London conference involving Britain, the Muzorewa government and the Patriotic Front of Robert Mugabe and Joshua Nkomo that laboriously carved out the agreement establishing the temporary British administration to supervise elections for a black-majority government. British Foreign Secretary Lord Carrington frequently complained, with some humor, that his role as chairman was a thankless one as he came under attack from both sides.

Soames maintains that his is a caretaker administration with no responsibility to impose upon Rhodesia any particular pattern of change.

It would be difficult, in any case, with only 64 British officials on the governor's staff and 10 local hires -- none of them African. In addition, there are 1,300 Commonwealth monitoring troops, about 100 election commissioners and a couple dozen police advisers.

Nevertheless, the protests continue and there is little question that the most serious are coming from the guerrillas and their supporters. The British in turn say that cease-fire violations, mainly by Mugabe's forces, represent the biggest single threat to successful conclusion of free and fair elections.

The main guerrilla complaints involve:

Allowing South African military units to remain in Rhodesia;

Authorizing the use of Rhodesian security forces against recalcitrant guerrillas who have not reported to assembly points as required by the London agreement:

Allowing "private armies," technically under the authority of the Rhodesian military but politically loyal to Muzorewa, to operate freely in parts of the country despite the terms of the London agreement:

Failing to stop or alter a variety of actions by civil servants which give the impression that the Muzorewa administration is carrying on business as usual.

The issue of South African military units in the country has been the most sensitive problem in black Africa where concern runs high about possible South African intervention. Britain maintains that fewer than 200 South Africans are guarding the southern access route to the country through Beitbridge and this does not represent an "intervention" force prohibited by the London agreement.

The guerrillas and their supporters say South African units that were elsewhere in the country were simply dissolved into the Rhodesian military, thus qualifying as part of the legal forces through subterfuge.

Few persons would dispute the real reason for the South African presence at Beitbridge -- to reassure the whites by providing an "escape route" south if things don't go to their liking.

The use of security forces against unassembled guerrillas is potentially far more explosive since a major outbreak of fighting could lead to a breakdown in the fragile cease-fire, thus jeopardizing the election. There are reports, denied by the British, that they had little choice in the matter: if Soames had not authorized their use they would have gone out on their own after the Jan. 4 deadline for assembling.

The reports are a measure of just how fragile Britain's control of its colony is and how much it must rely on good will. The fact that there have been fewer than 20 guerrillas reported killed since the security forces deployed -- in a country where no quarter has been given to the enemy -- is evidence that the mainly British cease-fire monitoring force has had some impact on the attitude of Rhodesian military.

One of the key problems the British face in the forthcoming election is intimidation of voters. Muzorewa, supported by Soames this week, charges that guerrillas who have refused to report to assembly camps will be used by the Patriotic Front, particularly Mugabe, to gain support from voters.

The Front, on the other hand, says that the auxiliaries, briefly trained troops loyal to Muzorewa, have moved into tribal areas vacated by guerrillas now assembled in camps and are intimidating voters.

British sources leave little doubt that the colonial government takes the guerrilla threat more seriously and openly hint that the auxiliaries will be curbed only when the guerrillas have abided by the cease-fire. Soames says the auxiliaries "are an important element in maintaining security."

Put bluntly it is a case of using one form of intimidation to counter another in a country that is a armed camp.

Probably the main area where the Soames administration is vulnerable to criticism is in the activities of civil servants from the Zimbabwe-Rhodesian government who are new responsible to Soames and carry out day-to-day government.

Customs and immigration officials have harassed Front officials returning to the country from exile as well as some Western journalists who had long been banned. Election campaign material has been temporarily confiscated, ostensibly pending payment of customs duty, giving an advantage to Muzorewa and other internal leaders who have had the ability to produce their political documents in this country.

The Rhodesian military continues to put out dailyy communiques that speak of alleged cease-fire violations and crimes only by the guerrillas. A British source admitted that it was "passing strange" that in almost a month of such reports since the London agreement was signed Dec. 21 there has not been a single case reported in the communiques of violations by the military or auxiliaries.