Possible Clues:

• Piano style
• Type of piano
• Little one played near older relative in the pits?
• Angry, hammered on key in poor-quality piano
• It has many keys but no locks
• Recent arrival with a £1000 instrument
• Instrument touching on rag out of place in orchestra
• The kid is splendid; play with it
• Parlor filler, perhaps
• Infant piano?