According to his profile, his parents were both over 100 years old when George was born. I believe the father's name (William) is correct, but Sir William Manwaring (1396 - 1499), son of Randle Mainwaring of Over Peover, is the wrong William.
Both Family Search (G6MW-ZB5) and Ancestry list William Manwaring born circa 1477 in Cheshire, death circa 1540, wife of Margaret Titley(Tytley) as father of George Manwaring.