LONDON — Two ancient Egyptian skulls unearthed in a yard in England have been returned to their native country. And the mystery of how they got from the hot sands of Egypt to the rainy north of England has been solved, investigators said Tuesday. The first skull was discovered by homeowner Matthew McClelland as he did some gardening at his home in the northern city of Manchester a year ago. He called authorities, and they discovered a second skull. An analysis by an Oxford University expert confirmed the skulls were a little more than 2,000 years old.