London — Dodging the bombs and bullets of Beirut, about 100 Queen's Dragoon Guards and other British troops crisscross the city in small armored cars gathering intelligence.
For the moment, the government of Margaret Thatcher intends to keep them there, alongside much larger United States, French, and Italian contingents in the multinational peacekeeping force.
The prime minister has made it clear that any decision to withdraw would be made jointly with the other countries. Mrs. Thatcher also said there is no possibility of augmenting the Dragoons with extra men.
As long as none of the British troops are killed or seriously wounded, there is no significant political opposition here to their staying on. The only real setback so far has been to the ex-commander of the force, Lt. Col. David Roberts , who was evacuated to Cyprus suffering from what was said to be ''exhaustion.''
The question is how long the British will or can remain. London has had to send six Buccaneer aircraft flying over Beirut from Akrotiri in Cyprus in a show of force. The planes are available to hit ground targets to protect British troops below.
More pressure on Mrs. Thatcher will come when Parliament returns from its summer recess, and if the troops begin suffering casualties.
The small British force went into Beirut to boost the government of Amin Gemayel (and, some here say, implicitly to protect Palestinian groups) in February. The British went in for three months. Later the period was extended to six months. Now a Defense Ministry spokesman says London has agreed to ''another limited period.''
So far calls for withdrawal have come from some Conservative backbench members of Parliament and from the outspoken and often controversial Enoch Powell, member of Parliament from Northern Ireland.
The prime minister can shrug off this kind of pressure, given her large majority in the House of Commons and what political sources see as the Labour Party's reluctance to take any stance these days that might lead to the charge of appeasement abroad.
Shadow foreign secretary Denis Healey, a Labour moderate, has urged Britain to join with France and Italy to put joint proposals to the US. He believes the US wants to turn Lebanon into a Christian protectorate dominated by the Phalange , whereas the European members of the peacekeeping force want a shift in power toward Muslim groups.
As the US began using offshore naval fire, and after the French had threatened to bomb anyone firing at their contingent of some 2,000 men, London sent in its Buccaneer aircraft and sent out a junior Cabinet officer for moral support. The minister, John Stanley, was unable to leave British headquarters in Hadaath in the southeastern suburbs of Beirut Sept. 19 as Lebanese Army 120-mm guns pounded guerrilla positions.
The mission of the British units is to ''act as the eyes and ears'' of the Lebanese Army and of the peacekeeping force, defense officials say. The troops have been caught in cross-fire, but they are under orders to stay out of any fighting unless directly attacked.
Mr. Powell claims Britain is slavishly following the US lead in Lebanon, but that ''it does not matter to the United Kingdom and its people who is in Beirut or who governs Beirut - the matter is one of the utmost indifference for the United Kingdom.''
When the first British soldier is killed, Mr. Powell told a political meeting Sept. 16, and the question is asked, ''What are we there for?'' the answer will be ''to assist the Lebanese government control Beirut'' and support US ''intervention.''
The Times of London dismisses this view. ''Nothing could be more damaging'' than a peacekeeping force pullout, it said Sept. 20. It would merely encourage Syria and work against reaching a local balance of power.