If art in America and Britain is to be "democratized," its financial support must come primarily from the public rather than the private sector, a visiting art expert said last night.

Addressing a crowd of about 150 people at the Kennedy School of Government, Sir Rov Shaw, secretary-general of the Arts Council of Great Britain (ACGB), said, "The principal source of art subsidy should be the state."

Shaw added that only with financial support from public organizations like the ACGB and its American counterpart, the National Endowment for the Arts, (NEA) can art "be made effective outside the clique of the learned and the wealthy."

"Subsidies from business can be capricious." Shaw said, adding, "Often-times businesses use their financial support of artistic productions like the theatre and the opera as public relations campaigns."

Public financial support creates its own unique problems. For example, the British government does not directly influence the arts agency's administrative decisions, but Prime Minister Margaret Thatcher has cut the ACGB's $85-million budget by $3 million in the last three years.

Shaw added, however, that the American NEA, whose budget was recently cut in half, faces worse fiscal problems. "Mr. Reagan is ahead of Mrs. Thatcher in these things." Shaw said.