Question: In which round did Roy Salvadori won Class D and Alan Hutcheson won Class B?
SQL: SELECT "Round" FROM "1-24853015-1" WHERE "Class D Winner" = 'Roy Salvadori' AND "Class B Winner" = 'Alan Hutcheson';

Question: When did Alan Hutcheson won Class B on round 1?
SQL: SELECT "Date" FROM "1-24853015-1" WHERE "Class B Winner" = 'Alan Hutcheson' AND "Round" = 1.0;