Yehudi Menuhin's influence continues to reach out a hand to young instrumentalists. His Menuhin Violin Competition for young players under 22 is internationally known; last weekend in the Waterloo Chamber of Windsor Castle - a staggeringly picturesque setting - some exceptional violinists, violists and cellists sought the laurels at the Windsor Festival International String Competition, Britain's major professional prize for string players set up in Menuhin's honour three years ago.