CREATE TABLE table_77932 ("Race Name" TEXT, "Circuit" TEXT, "Date" TEXT, "Winning driver" TEXT, "Constructor" TEXT, "Report" TEXT)

What company constrcuted the vehicle with a circuit of oulton park on 15 april?
SELECT "Constructor" FROM table_77932 WHERE "Circuit" = 'oulton park' AND "Date" = '15 april'
SELECT "Constructor" FROM "table_77932" WHERE "Circuit" = 'oulton park' AND "Date" = '15 april'