It was like bringing coals to Newcastle: the accent was decidely British - roast beef and Yorkshire pudding, Victorian nosegays for the ladies, and for the guest for honor, at least one Welsh tune.

Even one of the singers chosen to serenada British Prime Minister James Callaghan at the White House, last night American tenor Robert White, had a special British tie. His father, the late Joseph White who was known as "The Silver-Masked Tenor" back in the early days of radio, come had serenaded the English, too. That was in 1923 when his vioce was transmitted by wireless for the first time from the United States to England.

Yesterday, coming full-circle, singer White was sharing the White House rehearsal spotlight with mezzo-soprano Jan de Gaetani. Among his selections for the evening was the Welsh song, "All Through the Night" along with Gaetani's, "Jeanie with the Light Brown Hair."

The White House Stainway had been moved aside to make room for a 125-year-old Chickering square grand piano, borrowed from the Smithsonian. De Gaetani had sung to its accompaniment before and been so taken with it, said White, that she had asked the White House to borrow it for the evening.

For White, 36, the White House appearance was a return engagement, coming almost 14 years to the month when he and Basil Rathbone entertained at a state dinner the John F. Kennedys gave for Chalotte of Luxembourg. Then he sang Elizabethan songs; last night he selected ballads from the turn of the century.

De Gaetani, a professor of voice at the Eastman School of Music, chose selections from Stephen Foster.

The guest list also reflected British-American ties, with two former U.S. ambassadors to the Court of St. James's W. Averell Harriman and David K. E. Bruce represented.

Others included Vice President Walter Mondale and daughter Eleanor Jane, Mrs. Mondale was in New York on behalf of her husband, accepting the National Council of Jewish Women's John F. Kennedy Award.

Among the prime minister's official party were Foreign Secretary David Owen, British Ambassador SIR Peter Ramsbortham and Peter Jay, economics editor of the Times of London, who is married to Callaghan's daughter.