Death certificate for William Robbins (senior) states that his father was Charles Robbins, farmer England......his wife is shown as Johanna McCauliffe.
Perhaps McCauliffe is his mother maiden name??. As Graham is Johanna's maiden name.
On the birth certificate of Ernest Robbins son of William Charles Robbins junior...William shows his birthplace as Middlesex. On William Charles Robbins juniors death cert....his son lists his birthplace as Bristol.