Katie Derham hosts Proms Extra, the weekly Proms magazine show. The spotlight is on Beethoven's Missa Solemnis, the Borusan Istanbul Philharmonic Orchestra and the UK premiere of John Adams's Saxophone Concerto. Katie is joined by Han-Na Chang ahead of her conducting debut, celebrated trumpeter Alison Balsom and violinist Tasmin Little. Plus David Owen Norris presents Chord of the Week.