CREATE TABLE table_24853015_1 (round VARCHAR, class_d_winner VARCHAR, class_b_winner VARCHAR)

In which round did Roy Salvadori won Class D and Alan Hutcheson won Class B?
SELECT round FROM table_24853015_1 WHERE class_d_winner = "Roy Salvadori" AND class_b_winner = "Alan Hutcheson"
SELECT "round" FROM "table_24853015_1" WHERE "Alan Hutcheson" = "class_b_winner" AND "Roy Salvadori" = "class_d_winner"