Tip O'Neill always thought he did the best Gettysburg Address in the country. Then at Ford's Theatre last night where he and several hundred others were celebrating Abraham Lincoln's 171st birthday, he heard an Englishman do it.

"And you ran me right out of town," the speaker told Roy Dotrice, star and cast of the new one-man play titled "Mister Lincoln" which producer-director David Susskind is taking to Broadway later this month.

For Dotrice, O'Neill's praise was just another example of the reverential treatment he's been getting since the show opened in January. Shorter than the real Abe Lincoln, Dotrice nevertheless sports a very convincing beard, hairline and rumpled black frock coat.

Yesterday before the performance, he walked into the Beef Feeder restaurant across from Ford's and the whole place started singing "Happy Birthday" when the management brought out a slice of cheesecake with a candle on it.

People stop him on the street to say "Hi, Abe" and, after performances, seekk him out to tell him they couldn't hear his English accent.

"It is very strange until I realized that the [American] accent I spent hours in the BBC archives learning wasn't an accent to them," he said. "I keep forgetting I'm a foreigner."

So did everyone else last night, until they heard him at the party. Then his English accent was back and none the worse for wear, thank you, in the company of British Ambassador and Lady Henderson and the evening's special guests, Canadian Ambassador and Mrs. Peter Towe.

It had been at the Citadel Theatre in Edmonton, Alberta, in fact, that "Mister Lincoln" had its world premier, last fall. Ford's executive producer, Frankie Hewitt, flew up to take a look, convinced that after 12 years without a single Lincoln play, reports about "Mister Lincoln" by Herbert Mitgang finally warranted her attention.

"You may not believe this," she told the crowd, "but I've read at least 35 plays about Lincoln over the years since Ford's reopened. This year I got three Christmas cards from actors wanting to play Lincoln.

Lincoln's humor seemed to survive the age, reminding politicians like O'Neill and Rep. Phil Crane (-Ill.) that there's nothing like a good gag to help ther perspective.

"Absolutely essential," said Crane, claimed by his staff to be the first Republican congressman from Illinois since Lincoln to run for president. "You've got to be able to laugh at yourself."

That included laughing at his campaign adversary, the Manchester (N.H.) Union Leader, according to Crane.

"In fact, if we fare well up there, I intend to send that man [publisher William Loeb] a check for all his press work in my behalf. It won't be more than a dollar because I know it's going to stick in his craw."

Crane's wife Arlene, smarting over descriptions of her as, among other things, "abrasive" and "ambitious," said she certainly wouldn't want to be thought of as unambitious. "You know what they say, that behind every great man is a woman pushing him."

O'Neill called Lincoln's soliloquies "the basics of politics -- the packaging may be different but the basics never change."

And David Susskind, claiming to have "practically sold one major TV network the taped version filmed last night of "Mister Lincoln," told everyone in sight he invited President Carter over to see the show.

"Too bad, though, that he couldn't make it," said Susskind. "He needs to commune more with President Lincoln."