After a twenty minute search, Mycroft finally found his brother glaring up at Vernet's 'Self-Portrait' where it hung in the upper hall.
"It's wrong," said Sherlock.
Mycroft stood beside his brother, placed a hand on his shoulder in case he should try to run off again, and studied the painting. "What's wrong with it?"
"The room's full of dust, and the stove he's leaning on would be sooty. How could those white trousers stay so clean?"
Mycroft nodded. "A fine observation, but remember, Sherlock, this isn't a photograph; it's a self-portrait. Our great-grand-uncle painted this as an exercise in self-expression and metaphor. The fact he remains untouched by his filthy surroundings was a rather daring political statement. What else do you think he was expressing?"
"The drum, the pistols, the sword and dagger – they have to do with war."
"He wasn't a soldier, though. Not with that haircut, not standing like that. Maybe they belong to someone else, another man? But why would he put someone else in his self-portrait, and then not even show him?"
"Perhaps he lost his soldier in the war," Mycroft suggested.
Mycroft felt Sherlock's shoulder tense for a moment before he pulled away and dashed down the stairs.
Mycroft sighed and reminded himself that, for all his intellect, Sherlock Holmes was just a boy.