A large Half-Blood Prince IMAX poster, spanning about 13 metres by 10 metres, is being given away in a competition set up by the National Media Museum.

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To participate, simply email the answer to the following question:

Which of these Harry Potter characters is the largest?

1. Hermione
2. Hagrid
3. Horace Slughorn

The contest runs until August 3, 2009. In case anyone is wondering, the winning poster must be picked up at the museum, located in London, and no travelling expenses will be paid for. Good luck to all those competing!