The McLean Symphony performed a strong program of 20th century music at the Rock Spring Congregational Church Saturday night that showed major improvement in the string section since last season.

The program was one of two concerts this year devoted to modern music, with prominent strings in three of four pieces.

The string sections under Dingwall Fleary, the symphony's music director, have made significant progress since a weak performance reviewed last year. In the first and last movements of Gustav Holst's "St. Paul's Suite for String Orchestra," the players captured the jaunty sentiment of the English folk tunes Holst employed, achieving dense textures and distinct phrasing. Christopher Spooner, who replaced concertmistress Eve Adamopoulos, played particularly well during solo passages of the second movement.

While the strings were forceful in executing passages that required a unified sound, there were flaws in the integration of diverse voices. Samuel Barber's Adagio for Strings, which was used as background music for the movie "Platoon," is a simple piece, but it requires pinpoint accuracy to reach the emotional peaks that have made it a staple of American repertoire. The McLean group fell short of the test.

Mickey Thomas Terry, an organist for the chapels of Fort Myer, invigorated the evening with an ebullient reading of Francis Poulenc's wildly eclectic Concerto for Organ, Strings and Tympani. Terry maneuvered through particularly sharp shifts of dynamics without a hitch, in one instant opening up the full power of the 27 rank organ, in the next playing delicately.

The final piece, Paul Hindemith's Concerto for Organ and Chamber Ensemble, brought the McLean wind and brass out for what Fleary called "the most 20th century piece" on the program. A precise performance by Terry and the McLean musicians instilled a machine-age sensibility in the music. With a less imposing organ part than in the Poulenc, the Hindemith calls for featured playing from many members of the group. The sense of ensemble was dramatically improved over previous pieces.