CREATE TABLE table_24853015_1 (round VARCHAR(255), class_d_winner VARCHAR(255), class_b_winner VARCHAR(255))
In which round did Roy Salvadori won Class D and Alan Hutcheson won Class B?
    
SQL: SELECT round FROM table_24853015_1 WHERE class_d_winner = "Roy Salvadori" AND class_b_winner = "Alan Hutcheson"