Roy Salvadori ชนะคลาส D และ Alan Hutcheson ชนะคลาส B ในรอบใด?ไม่จำเป็นต้องใช้โต๊ะทั้งหมด
In which round did Roy Salvadori won Class D and Alan Hutcheson won Class B?It is not neccessary to use all the tables.
 table_24853015_1:  (round [ VARCHAR ] class_d_winner [ VARCHAR ] class_b_winner [ VARCHAR) ]
SELECT round FROM table_24853015_1 WHERE class_d_winner = "Roy Salvadori" AND class_b_winner = "Alan Hutcheson"