You hardly expect a children's orchestra to be allowed to give a world premiere. But Yorchestra, York's holiday orchestra, which attracts players from all over the county and beyond, achieved that honour in splendid style.

This was no ordinary piece. George Fenton, composer of countless film and TV scores and winner of four BAFTA awards, personally gave conductor Janet Fulton permission for Yorchestra to become the first amateur group anywhere to play Our Planet Is A Blue Planet, his (unpublished) theme music to BBC Television's oceanic series.

It was the culmination of an evening that revealed astonishing results after a mere three days of rehearsals.

A jazz group opened up with some smooth, leisurely blues concocted by its piano-conductor, Danny Gough. Janus Wadsworth's confident wind band, with eight trumpets and a battery of percussion to the fore, offered a suite from West Side Story, and selections from John and Robbie Williams.

The 15 strings of the first orchestra, under Penny Stirling, attacked three of Bartok's Transylvanian dances with infectious enjoyment, unfazed by some tricky syncopation.

Her larger string group proved equally nifty in a fast movement from Nikolay Rakov's Sinfonietta.

The full orchestra, some 60 players very capably led by James Woodrow, stuck to a nautical theme: first a fantasia on sea songs under Dan Shilladay, before Miss Fulton secured a thunderous climax in the big tune from Khachaturian's Spartacus.

Then the big blue whale surfaced - and took everyone's breath away.