Push up, pin up Doctor...
It's Anderson who finds the stash during one of the Yard's weekly Drugs busts. He and Sally are rummaging around in Sherlock's room looking for anything particularly disturbing or strange. With most of Sherlock's stuff falling under this category makes the task just a tad more difficult. Sally is being useless (as usual) and is fiddling with a puzzle box positive it is stuffed with drugs.
"As if the freak would be so obvious." He thinks. He doesn't say anything though and lets her fiddle with the catch. She paces around the room as she struggles treading on a squeaky wooden floor board as she does so. With each pass of the room the board wines noisily irritating the hell out of Anderson until he can bare it no longer.
He goes to pull the damn box from Sally's grasp when he has an epiphany. Shoving Sally out the way and tossing the box aside he crouches down to test the floor. He locates the loose board easily and pulls it up using his fingernails.
Anderson nearly throws up at the sight of his discovery. "Fucking hell" he says pulling up more and more evidence. He momentarily considers putting it back and pretending it doesn't exist but the mental images wont leave his head. Besides Sherlock is sure to know he's seen it anyway. Feeling sick he begins to bag it all up with wobbly hands when Sally plucks some of the photographs from his gloved fingers and lets out a shaky gasp that's quickly followed by a laugh.
She quickly flicks through the handful of photos before he can stop her. A smile creeps up her face and she whistles as she examines them, letting out a string of comments as she does so.
"Well this explains why John's stayed so long"
And "So much for being room-mates"
"I've never seen a walking stick used quite like that"
"No wonder the freaks so happy recently"
"Oh now that's really kinky"
And as she comes to the end "I don't think I can ever eat jam again". Anderson blanches and Sally smirks at him as she slips the photographs into her jacket, a certain evil glint in her eyes. "You know I think these would make a wonderful calendar for the office."