Sykes was born in Oldham, Lancashire; his mother died three weeks after his birth. He was the second child of his parents' marriage; his older brother (by two years) was named Vernon. Sykes's father was a labourer in a cotton mill and a former army sergeant. When he was two, his father remarried and he gained a half-brother named John. Sykes was educated at Ward Street Central School in Oldham. He joined the Royal Air Force during World War II, qualifying as a wireless operator with the rank of Leading Aircraftman.