Possible Clues:

• Unaffected - native
• A note that's quite ordinary
• So a turn that's twisted over half a century is quite usual
• Certainty is only to be expected
• Normal - instinctive
• Unaffected - innate
• In the ordinary way one might thus give a turn a twist with a pound
• Not synthetic or man-made
• Unaffected or earthy
• Instruction to cancel flat?