On this side of the Atlantic, many Presidential campaign strategists of both parties greatly admired the way it portrayed Mr. Kinnock, who subsequently lost to Prime Minister Margaret Thatcher, as a man of character. Senator Joseph R. Biden Jr. of Delaware, a Democratic hopeful, was particularly taken with it.

So taken, in fact, that he lifted Mr. Kinnock's closing speech with phrases, gestures and lyrical Welsh syntax intact for his own closing speech at a debate at the Iowa State Fair on Aug. 23 - without crediting Mr. Kinnock.

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At various campaign appearances last month, the Senator talked admiringly about Mr. Kinnock's themes and incorporated phrases and concepts after first crediting the Briton. But, in his closing remarks at the Iowa State Fair forum, he did not mention the Labor leader, nor did he some days later in an interview when he recounted the positive response. Biden Elated at Iowa Debate

''I feel real good about that Iowa debate,'' he said. ''I could tell when I was doing my close - that whole audience was absolute dead hushed silence. You can tell when you have it all. And the reason it worked there was, I was the last one. And I decided, I have no close. I didn't have a closing. I'm walking in and they're saying, 'You're going to this debate,' and I said, 'I don't like this stuff you've written for me.' ''It fit to do that there.'' Advisers to the candidate said that, when it was pointed out to him after the debate that he had followed the Kinnock speech very closely, he was surprised and said he had not been aware of it. They stressed that the Senator had been immersed in difficult preparation for the hearings on Judge Robert H. Bork's nomination to the Supreme Court, an important test for Mr. Biden's political future.

''He was not trying to put something over,'' said one adviser. ''He's under a huge amount of pressure. He didn't even know what he said. He was just on automatic pilot.''

But Mr. Biden's borrowing raises questions about how much a candidate can adapt someone else's language and thoughts, whether he remembers to give credit or not.