[ To her credit, Sherlock has not yet figured out she's a spy, but he is acutely aware that there's something not quite average about her. Give him time. ]

Ah, well. [ He looks around, making a vague gesture. ] Unless his portrait is going to spring to life, John isn't here. You'll have to do in the meantime. As for trust - I trust John's judgement of character.

[ Please do not tell John he's said that. ]