A reporter reflects on Britain after the Falklands

It often happens. You ask a child to tidy his room or clean his shoes, and later he looks at you blankly when you remind him: all he remembers is that you said he could watch television. An office colleague distinctly heard you say you would be out all afternoon when in fact you said you'd be back in 10 minutes.

When I was a young reporter in Australia, a stentorian assignment editor dispatched me in an office radio car to write a breathless story about a baby miraculously saved in a car accident by being thrown from a window onto a grassy verge. When I arrived, cars and police had long since gone, so I started, dutifully, talking to people nearby.

Without any difficulty I found three who had definitely seen a baby happy and well near one of the cars - and three more who swore that, no, there had been no baby at all, only adults. There was a story there but not the one my editor wanted at the time.

People see the same event and reach opposite conclusions. Who is right? Perceptions become more important than ''facts'' - a lesson that US and, increasingly, British politicians have been learning.

Take Britain in the period following the 74 days of the Falklands war. Britain is a lovely country to look at, but its heart is troubled and restless. Former US Secretary of State Dean Acheson's prophetic remark still rings true: The empire is lost but a new role is yet to be found.

Has the victorious Falklands campaign at the other end of the world calmed that restlessness or helped unearth a new role? Well, it depends on the perception you carry away from the war, which blew up like a sudden storm at sea , with little warning.

If Prime Minister Margaret Thatcher herself was surprised, as she has told friends, imagine how astonished the man in the street must have been.

One perception is that Britain scored a brilliant success. In fact, some believe, the month of June 1982, which also saw the birth of a new prince, was the best Britain has enjoyed since the summer of 1953 when a Britain preparing to crown a queen was delighted at Edmund Hillary and Sherpa Tenzing Norgay conquering Mount Everest almost the night before.

The Fleet Street tabloid press has tried to whip up jingoistic sentiment about the Falklands, aiming at a supposed clientele of middle- and lower-middle-class readers said to love memories of empire and all things military.

A columnist for the Daily Express, complacent to the core, even attributed the royal birth and the Falklands campaign to ''the consequence of our having been a good and true people.'' None would deny the goodness and truth in the British character, but the columnist succeeded only in sounding naive in his self-congratulation.

Retired admirals, generals, and air marshals are of course pleased with the Falklands success. Well-to-do areas in Surrey and further south are proud. British soldiers fought well and skillfully, showing the virtues of tough training in Norway and duty in Northern Ireland.

The feeling may grow, I think, that the government now faces an even greater challenge. Since military action is seldom a final solution, Mrs. Thatcher must find a way to a lasting settlement in the South Atlantic. Instead of denigrating the Argentines at every opportunity, she may have to come to the view that they must be talked to, if only because they live a mere 400 miles from the Falklands , while she herself remains 8,000 miles away.

There are also the bills to be paid - three quarters of a billion pounds this financial year alone. A mighty battle is beginning behind the closed doors of Whitehall ministries over the insistence of John Nott, the controversial secretary of defense, that all extra spending for the war (chartering civilian ships, for example) be paid by the treasury and not by his own annual defense budget of (STR)14 billion ($24.3 billion). However, the perception of many people so far is that Mr Nott's military operation has boosted British pride to at least some extent. But there is another perception altogether of the British mood. Trade unionists, far from being suffused with a new ''common aim'' and sense of purpose as the Daily Express would have us believe, are too busy going on strike to think about it.

''I really don't believe,'' as former Cabinet minister William Rodgers observed in a splendidly panelled House of Commons sideroom the other day, ''I really don't think much of this so-called new spirit has rubbed off on the railway workers . . . .''

He had a point there.

British Rail was already preparing for a nationwide strike. I was told by sources at No. 10 Downing Street that trains could disappear completely for two or three months, at a catastrophic cost to the steel, coal, auto, chemical, and other industries, not to mention to British Rail itself.

At the last minute the union threatening the strike - the National Union of Railway (NUR), which covers guards (signalmen) on trains, went back with BR for more talks. But, just as Britain heaved a sigh of relief, the men who drive the trains immediately called a strike of their own, in implacable protest against a BR plan to introduce so-called ''flexible rosters,'' in place of the drivers' traditional eight hour work day.

A country which had thought it had regained its trains suddenly found it had lost them again. Nor was that all. National health nurses in full uniform were on strike for higher wages, and standing outside coal mines begging miners to stop work in sympathy. This directly breaks a 1980 law which bans so-called ''secondary picketing'' (striking in sympathy for another, unrelated, union). On June 23, workers in shipyards, factories, and water boards, and local council and government offices also went on strike to support the nurses.

It was as though a truce on such everyday economic and social issues, which held during the war with Argentina, had suddenly broken. Britain was back to its argumentative self.

Rival rail union chiefs shouted at each other on television. On another program a national health union leader from the far left shouted at a Conservative Party backbencher, right through an interviewer vainly trying to question them both.

Plenty of opposing perceptions here: About right and wrong, about public duty and private need. Are you bothered about breaking the law? A television reporter asked a nurse in blue cape and nurse's cap as she tried to stop coal miners working. No, came the measured answer. The law should be more sympathetic to national health workers.

Underlying class and social division are again on display, as they are across the spectrum of British life. The well-off and those with jobs denounce blue collar workers and rejoice in the war victory. Unionists denounce bosses across a divide of class prejudice and tend to consider the war, now that it is over, an expensive and basically irrelevant issue or, as one young worker put it to me , a ''tragic waste of lives.''

Most people questioned by the polls supported Mrs. Thatcher while the war was being fought, but the mood could swing as the bills come in, as unhealed social and economic problems clamor for solution in a country where 3 million people ( 12.8 percent of the workforce) remain unemployed.

Now, even more than ever before, the skill, the resolution, the bravery, and the intelligence that regained the Falkland Islands are all needed to tackle the less glamorous, less spectacular, but more fundamental challenge of class division, of economic and social antagonisms intensified by two decades of industrial decline.

No country can rely for long on oil revenues (in Britain's case, from the North Sea) to sustain a standard of living which ought to rest, instead, on genuine investment, not just of capital, but of new ideas.