Sam Johnson Hammered

Yesterday afternoon, some vandal took a hammer to Sir Joshua Reynolds' portrait of Samuel Johnson in the National Portrait Gallery, London. He smashed the glass, hit the painting a number of times and left his hammer embedded in the canvas. Security staff detained him until the police arrived and carted him off to Charing Cross Police station. Experts reckon the painting can be repaired. What beef does this twerp think he has with Samuel Johnson? Hates men in silly wigs? Confused by dictionaries?