CREATE TABLE table_58403 ("Race Name" TEXT, "Circuit" TEXT, "Date" TEXT, "Winning driver" TEXT, "Constructor" TEXT, "Report" TEXT)

Who is the constructor of John Surtees's Oulton Park circuit car?
SELECT "Constructor" FROM table_58403 WHERE "Circuit" = 'oulton park' AND "Winning driver" = 'john surtees'
SELECT "Constructor" FROM "table_58403" WHERE "Circuit" = 'oulton park' AND "Winning driver" = 'john surtees'