Possible Clues:

• '60s music invasion country
• Combination of three countries -- means to think about it
• It is where you think, this country?
• UK's largest island
• Rita trapped in chest with close neighbour
• Hogwarts setting
• Country girl fills silo
• Island with special quality requisitioned by Crown
• Great place — keep it in mind
• Have you got it into your head that that's not here