The overall approach may not change much from year to year, but the anniversaries celebrated in this year’s Proms have generated a richer mix of musical styles and periods than in some recent seasons. There are works by William Byrd (15 July) and Thomas Weelkes (30 July) to satisfy the early-music enthusiasts, while those who love to indulge in the lusher end of romanticism will relish the number of pieces by Rachmaninov included to mark the 150th anniversary of his birth, though there’s no sign of any of the operas or even of all of the piano concertos. Followers of 20th-century music will welcome the healthy representation of pieces by Ligeti, including his celebrated Requiem, in his centenary year. Another 100th milestone, marking the Croatian composer Dora Pejačevič’s death, provides the opportunity to explore some of her little known output; and, if the new works and commissions are generally rather disappointing this time, with very few truly outstanding world premieres in prospect, then the rarities dotted throughout the programmes will be some compensation.