AMERICA'S NATIONAL PASTIME includes strikes. In Great Britain, it is strikes. Take this summer's "industrial actions," for instance.

Getting to work or play called for some serious ambulatory action, separate strikes shut down the national rail system twice and the London Underground subway once. Getting to the nation's free national health service called for some serious luck, the service's nurses union punctuated the summer with periodic strikes and slowdowns. If you wanted to read about all the troubles, you might be stymied too, the venerable Times of London didn't come off the presses for several days, thanks to a printers' strike. And if you just wanted to get away from all the pickets lines, well, that too was easier said than done. The workers on the Sealink Ferries to Europe walked out in mid-summer.

The British have responded with a typically still upper lip. If Her Majesty's forces could travel more than 8,000 miles to fight in the cold of an Antarctic winter, the citizenry felt it could withstand a four-hour highway trip home in a moving parking lot, or bunking down overnight in the office with a sleeping bag.

It's not unusual for Britain to have lots of strikes, each major trade union has had plenty of arm wrestles with successive Governments over the last 30 years. Just this winter, there were 17 separate industrial actions. What is different is Prime Minister Margaret Thatcher's renewed attempt to break the union's power grip on the country's services. She's risking economic disruption in the mids of a nation-wide economic downturn.

Whereas in the last 30 years a British Government's capitulation to organized labor's demands after a brief strike had become almost a ritual, the Iron Lady has begun to test the unions' mettle. The unions might have been running the show in the past, but no more Thatcher defused each strike this summer just by standing her ground.

NOW BRITISH UNIONS have certainly run roughshod at time, but Thatcher is going too far in her anti-trade union crusade. With the British economy deathly ill, she's right to want to cut costs and increase productivity. But economic recovery won't come without the cooperation of the now-humbled labor movement.

The U.S. faces the same bleak economic picture. Industrial recovery, as Chrysler learned, can come through close cooperation with organized labor. Yet President Reagan, formerly of the Screen Actors Guild, seems to have no more regard for unions than his counterpart across the Atlantic Reagan's wholesale liquidation of the air controllers union. PATCO, and his proposals for a flexible minimum wage and child labor standards fly in the face of trade union principles.

Thatcher and Reagan aren't fully wrong, they should reign in some unnecessary union prerogatives. But the virulent anti-union bias of the two leaders is preventing the industrialized world from recovery.

In Britain, it's the government that negotiates almost every labor contract, not private industry, so Thatcher has a lot more direct clout than the American president. She knows she has the public's tacit approval to hold the line. But unemployment's at 14 percent and rising, and the persistent work stoppages and management-labor animosity that the prime minister has done nothing to discourage are contributing to the slump. In such a situation. Thatcher can't afford to seek an unconditional surrender, only an evenly negotiated truce.

Reagan can't throw his weight around as easily as Thatcher, but he's certainly got the ability to encourage industrial compromise. The government's seal of approval was evident on the comeback of the Chrysler Corp., which quietly reported large profits last quarter. The agreement in that case: The United Auto Workers permitted fewer immediate benefits, in return for a spot on Chrysler's board of directors. By contrast, look at the recent demise of the Checker Cab Company. Its employees refused to make short-term concessions; they ended up without a company--or jobs.

One fertile ground for compromise is the new concept for flexibility in labor markets. Britain and the U.S. for long have operated under the principle of rigidity of labor--eight hours a day, five days a week, nothing more. In return for job guarantees, employees could work in a more flexible, hence productive system. That innovation has helped. Japan's fine-tuned economy, which--at least by comparison--is flourishing.

Judith Hart, a member of Parliament, recently described the role of unions nicely: "...the trade union movement in this country is part of our democratic inheritance, fought for in hardship, established in realism." It's time for some of that realism to creep into government policy towards labor both here and in Britain before both economies get even worse.