A dejected Labor government is counting the political cost of a strike wave that is likely to carry Conservative Party leader Margaret Thatcher to power before the year ends.

A poll published in the Daily Express today gives Thatcher's Tories a crushing 55-36 percent lead over Labor. That would provide them with a margin of about 150 seats in the House of Commons.

Only three months ago, before the truck drivers and blue-collar government workers began walking out, the major parties were neck and neck. The Tories then held a 47-46 edge.

"This is as quick a shift as I've ever seen," said Robert M. Worcester, whose Market and Opinion Research International took the sampling. To rub salt in the government's wounds, Worcester, an American living in London, is the Labor Party's private pollster.

For the first time since comparisons were made, Thatcher is more popular than Prime Minster James Callaghan. Dissatisfaction with his performance has skyrocketed in three months from 31 percent to 61 percent. In contrast, nine people now say they are "satisfied" with Thatcher for every eight who are "dissatisfied."

Callaghan has been counting on his public amiability to score against the more aggressive Thatcher in a campaign, but even that prospect is now fading.

An election must be held no later than Nov. 10, and the conventional wisdom here assumes that Callaghan will hold off almost to the last moment to put the maximum distance between the strikes and a vote. But he may be driven, or even choose, to face the voters earlier. There now appears almost no way he can escape the consequences of his own union followers' strikes.

One Labor strategist was asked today whether there was anything the government could do to save itself. "Pass a bill putting off the election to 1984," he quipped.

The truck drivers have gone back to work with pay increases of about 21 percent plus some fringe benefits. But the country is still plagued by on-again, off-again strikes of low-paid manual workers in local government service.

Garbage men are out in many neighborhoods, including central London, and mounds of black plastic bags, heaped with trash, mount higher. School children get unexpected holidays because kitchen workers and janitors demonstrate. Perhaps half the hospitals are admitting emergency cases only. Kitchen and laundry workers, floor cleaners and ambulance drivers are providing only limited service.

These workers typically make $75 or $85 for a 40-hour week and are demanding a minimum of $120. With bonuses and overtime, they actually gross from $90 to $170. Britons work more overtime and holidays than other Europeans but the pace of work tends to be more leisurely.

A virulent campaign by a predominantly Tory press has helped build sentiment against the government. Recent tabloid headlines have cried, "It's No Mercy Until Further Notice" and "Target for Today -- Sick Children" and "What Right Have They to Play God With My Life?"

In fact, reporters who have examined the strikes closely agree they have caused far more inconvenience than danger. Strikers have worked out arrangements, hospital by hospital, plant by plant to provide vital supplies and services. Waiting lists for routine hospital treatment have lengthened; nurses, administrators and volunteers have had to collect laundry, cook meals and even clean wards. But no one has yet traced an injury or an illness to a walkout.

Exaggerated slogans also marked the truckers' strike, which was billed as "paralyzing" the economy. The well-regarded Economist magazine has been running indignant articles about the crude misinformation produced by the government and employers.

But no one denies that the ultimate economic consequences of the strike settlements will be severe. Inflation here was brought down from 30 percent to 8 percent by workers' painful acceptance of wage restraint. But deals are now being made for pay increases of 15 percent and more. Short of draconian tax increases, it is hard to see how inflation can be kept from rising above 10 percent again by the end of this year.

Somehow, the impression has spread abroad that the strike wave is a "challenge to government," a repeat of the 1973-4 coal strike that brought down Conservative Prime Minister Edward Heath. It is not. Heath's pay curb was enacted by Parliament and the miners were defying a law.

This time, Callaghan has urged a 5 percent pay limit -- smashed weeks ago -- but it has no parliamentary sanction. On the contrary, Parliament stripped Callaghan of power to punish firms that breached the limit. He never dared put his 5 percent to the House of Commons because he would have almost certainly been driven from office.

The earlier years of pay restraint succeeded because the unions, and their members, gave the technique their support. This time, both the unions and Callaghan's party explicitly voted against restraint and for "free collective bargaining."

Even if union leaders had agreed to a fourth year of restraint, they probably would have been overridden. Talks with strikers reflect the same theme: we held back on pay to stop inflation. But prices are still going up, so we've been cheated. Now we'll get what we can.

Callaghan has already referred to what is happening as "free collective vandalism." The strike wave and the resultant push in prices are likely to produce at least two consequences here.

One is the revival of incomes policy or pay restraint on a continuous, institutionalized basis.

Twelve important and moderate union leaders have already issued a pamphlet urging an end to "an irresponsible free-for-all." In a plan that borrows from Sweden and West Germany, they propose a yearly meeting with employer and government representatives to forecast likely levels of output and what the economy can afford in wage increases. This "indicative norm" would guide bargaining and be supported by a government agency to police prices.

Callaghan has given this his blessing, but it is likelier that Thatcher may have to launch some such plan.

A second likely consequence is a call to curb union power by requiring secret ballots for strike votes and by outlawing secondary boycotts -- picketing of an employer not directly involved in a wage dispute.

The unions are trying to head off legislation by working out a voluntary code with Callaghan. He, in turn, hopes this code, due to appear in 10 days, will restore confidence in his leadership.

But the ranks want more and the end of the strike wave is not in sight. White-collar civil servants, power workers and coal miners are all threatening either big demands, walkouts or both.