Norman Lear's 'I Love Liberty': patriotism and family fun; Also, British invade US sitcoms with the sometimes-witty, early 1900s adventure series 'Q.E.D.'

The man whose TV theme song has been ''Those Were the Days'' (''All In The Family''), has now fervently switched to ''God Bless America.''

Norman Lear, in great part responsible for what has been called ''the golden age of TV sitcoms'' in the 1970s, is spending a good part of his time these days spreading the message that the American flag is not the exclusive property of the Moral Majority and other groups which he feels disdain individual political thinking.

''I Love Liberty,'' (ABC, Sunday, 9-11 p.m.), produced by People For The American Way, is an unabashedly patriotic, flag-waving, freedom-loving, electronic paean to America's diversity of people and attitudes. Just about every patriotic song is sung, just about every hero of American history is quoted in this rousing rally, a flag love-in taped at the Los Angeles Sports Arena to celebrate Washington's Birthday. The backdrop throughout the show is a 30-by-60-foot American flag.

Parts of this two-hour marathon of American pride, optimism, and goodwill may sound a bit like the dramatic rah-rah radio shows one heard during World War II in order to bring Americans together. As a matter of fact, Norman Corwin, one of the authors of such shows, is credited as consultant. Co-chairpersons for the event, by the way, are Gerald Ford and Ladybird Johnson.

Perhaps it was a little far out to enlist the aid of the Muppets' Miss Piggy and Kermit the Frog to reenact the deliberations of the Continental Congress, but when Barbara Streisand sings ''America The Beautiful'' it is apparent that show biz can be American biz as well. Viewers may find themselves clapping rhythmically with the big-band marching to the tune of ''Stars & Stripes Forever'' in one of the opening numbers featuring thousands on stage. Viewers are encouraged to join in the singing of such songs as ''This Land Is My Land,'' ''Yankee Doodle Dandy,'' ''Amazing Grace,'' and the grand finale, ''God Bless America.''

Mr. Lear managed to get Barry Goldwater and Jane Fonda on the same program saying basically the same things. Even the late John Wayne, in a film clip, comments upon how he disagrees with Miss Fonda but believes in her right to say what she believes.

Through the skillful use of songs, dance, dramatic skits, and recitations, ''I Love Liberty'' tries to wrest away from and then share the mantle of patriotism with those who insist upon using the flag as their exclusive cloak. It invests the love of freedom, liberty, and the flag symbol itself with a kind of natural and refreshing sophistication in which all Americans can join unashamedly.

However, besides championing good old-fashioned patriotism, ''I Love Liberty'' succeeds in being good, old-fashioned family fun. A chat with Norman Lear

Although Norman Lear has given up active participation in his company's production of sitcoms, nobody is saying ''Whatever happened to Norman Lear?''

Hidden away at the end of a long corridor, amid the many cubicles at WNJV, New York's Spanish-language TV station, I find Norman Lear in his bleached-wood corner office, surrounded by huge tropical plants and panoramic views of New York City skyscrapers, symbolizing, perhaps, his own West Coast-East Coast ambivalence.

Dressed casually in a blue hand-knit sweater, he explains that his company owns WNJV, Channel 47. Most of the varied companies in film, TV, and cable with which he is associated now operate under the umbrella title of ''Embassy Communications Inc.'' Right now he is most involved in two films for theatrical release, ''Heartsounds'' and ''A Wrinkle in Time.''

''When I left the sitcoms last year, it was after around 2,600 half-hour shows. That part of my work life is over,'' he says contentedly. ''Now I am into other things. Maybe more important things.'' (Besides ''I Love Liberty,'' one of his projects is ''People for the American Way,'' a group with 60,000 contributing members formed as a patriotic alternative to the Moral Majority and similar groups.)

Does he expect controversy over the show?

''Not controversy,'' he says. ''But it will surprise a lot of people. If my hunch is right, it will touch a nerve with millions of people just the way the live show did in Los Angeles, where thousands of people joined hands and sang together with the actors.''

Is the show meant to be an answer to the Moral Majority?

''No,'' he says thoughtfully. ''I think in one way it runs counter to the Moral Majority tactics. But it's not an answer, not by design. We just want to counter all those many groups on the far right, sometimes the religious far right, who use scare tactics. They use fear of Armageddon if you don't commit to their politics, if you don't see things the way they see them. We are trying to affirm people's faith in themselves, whatever politics and religion they choose. The show tells you that you matter as an individual in this society. There's reason to hope, have faith in the future.

"There's a great repressed desire in a lot of people who haven't been heard yet to say 'Hey, wait a minute, that flag is mine also; liberty and freedom belong to me, too.''

For a long time too many people have been feeling that they don't matter, they feel alienated. And that is a self-fulfilling prophecy. I believe that the umbilicals that tie us together are by far greater than the things that disunite us politically. I have been a lifelong Democrat and Barry Goldwater has been a lifelong Republican, but we have no real differences when it comes to the First Amendment, the Bill of Rights, constitutional democracy, the American experiment , the American flag.''

Mr. Lear reveals that the Rev. Jerry Falwell of the Moral Majority, which he points out is only one of many comparable organizations, wrote and asked to be allowed to present his point of view on the air, adding significantly that he was sending a copy of his letter to the chairman of the Federal Communications Commission. Mr. Lear responded that there were to be no speeches per se on the show, so therefore there was no room for a Falwell speech.

An official spokesman for Mr. Falwell told the Monitor that ''The program is clearly designed to build credibility for People for the American Way and to help them get a mailing list. The Reverend Falwell has prepared a TV special 'God Bless America, Please' and has had to buy time for airings starting next week, while ABC has donated two hours of its time to Mr. Lear. We have no argument with his right to say what he believes, but we think Lear ought to pay, too.''

Mr. Lear responds that he followed ''the traditional show-business practice and submitted the special to ABC, which accepted it. I have followed that practice many times in the past.'' British invade US sitcoms

For the past decade American television has been importing British miniseries and adapting British situation comedy (''All In the Family'' and ''Sanford and Son'' were both based on English shows.)

Now a British producer is preparing a continuing series especially for the American market. ''Q.E.D.'' (CBS, Tuesdays, 8-9 p.m.) is created, co-written, and executive produced by John Hawkesworth, the distinguished Englishman responsible for bringing to TV such series as ''Upstairs, Downstairs,'' ''The Duchess of Duke Street,'' ''Danger UXB,'' and most recently, ''Flame Trees of Thika.''

''Q.E.D.'' concerns Quentin E. Deverill (Sam Waterston), a science professor ahead of his time who migrates to England in 1912 where he gets involved in mysteries, inventions, and all kinds of capers with his taxi-driver-cum-butler/chauffeur. The period, its costumes, and its customs are adhered to honestly, and the production is shot in England with lovely British locations.

I screened rough versions of this multifaceted adventure series, which is scheduled for the next six weeks on CBS, with the hope that it will be popular enough to go on to full-season series. ''Q.E.D.'' is strongest when it is most British and weakest when it tries to emulate American adventure series. Thus there are periodic chases, fights, physical movement galore - the kind available on any American adventures series. And it carefully draws from the American comic-strip tradition of a bumbling hero pursued by a constantly evil villain.

It is only when there is quiet, wry, witty dialogue that its British ancestry shines through. But as the series progresses from first to sixth week, it improves - mainly because Mr. Hawkesworth seems at last to acknowledge that he is the Englishman John Hawkesworth, not an American version of him.

It is a series worth watching if only because it represents an interesting initiative on the part of CBS, an attempt truly to try an innovative series, utilizing one of the world's finest and most innovative creative television talents, John Hawkesworth. It is a literate adventure series, simultaneously British and American. It works best British.