SOLUTION to General Knowledge No. 2,637:

Across - 7, Millefeuille 9, Nemesis 10, Sucre 11, Test 12, Anguilla 14, Nostromo 17, Yoda 20, Ryman 21, Niobium 23, Rostropovich. Down - 1, (Tracey) Emin 2, Glamis 3, Meuse 4, Jensen 5, Rimbaud 6, Glycol 8, Gelada 11, Tundra 13, Granite 15, Samson 16, (James) Monroe 18, Osiris 19, Colon 22, Mahé.