Sherlock had deleted most of the information about the Knights of the Round Table when he was very young, as at the time, he had dismissed it as silly fantasy.

He was regretting that decision now.

"Morgana." He said, hovering protectively close to John. "She is another wizard that attempted to kill me in the past." He made an educated guess. "And you believe that she or a reincarnation of her will attempt to attack you while you are incapacitated."