{TABLE} Concerto in D ........................... Stravinsky Piano Concerto in D K53 ................. Mozart Violin Concerto in D minor .............. Mendelssohn Variations on a theme of Frank Bridge ... Britten {/TABLE} THE Irish Chamber Orchestra's programme under Kent Nagano at the RDS on Sunday divided neatly into symmetrical halves around the interval. Each half gave us a mid 20th century work for string orchestra and a concerto, but the quality of both music and musicmaking created a division at a different juncture.

Stravinsky's Concerto for D, written in 1946 for the strings of the Basle Chamber Orchestra without a soloist, is at the lighter end of the composer's output, though it's typically sophisticated in its calculation of instrumental effect. The ICO's performance under Nagano (with a string body significantly below what the music calls for) traded on drive and energy but was not always tight in ensemble.

Mozart's Piano Concerto in D, KS 37, is not among the composer's best and the ICO's performance was not helped by the unexplained omission of all the non string parts - flute, oboes, bassoons, horns, trumpets and timpani.

Admittedly, the further reduction to single players for the string lines when accompanying the solo piano did at least do something to address the loss of contrast. But Mari Kodama's playing was far too straitlaced and expressively limited to bring any lively sense of chamber like interplay to the music, and, in spite of her embellishments in the slow movement and filling in of fermatas, there was no strong sense of Mozartian style to the performance.

The youthful Mendelssohn's strings only output is being heavily mined by the ICO. In the Violin Concerto in D minor the orchestra's leader and artistic director, Fionnuala Hunt, gave a technically strong reading which, in spite of some extreme manipulations of tempo and a cut in the slow movement, didn't really manage to mask the limitations of the 13 year old composer's work.

Happily, for the closing piece, the Variations on a theme of Frank Bridge which launched the 21 year old Britten to international fame at the 1937 Salzburg Festival, the playing was transformed, so much so that you might have been forgiven for thinking it was a different orchestra on the platform.

The assurance of the young Britten as he tried on a range of stylistic hats was matched by the ICO with eloquence and vitality. The sharpness of touch and fineness of detail, the sheer dynamism in this closing work stood out all the more clearly for the absence of these qualities in the earlier performances of the evening.