Officers from the Metropolitan Police mounted branch form a line during a practice session in Hyde Park in London April 24, 2011. On Friday, nine of the horses will accompany Prince William and his new wife Kate Middleton as they return from Westminster Abbey to Buckingham Palace. Picture taken April 24, 2011. [Photo/Agencies]

Armed police officers patrol a side street near Westminster Abbey ahead of this weeks' Royal Wedding in central London, April 26, 2011. British police promised they would crack down "robustly" on anyone trying to disrupt Friday's royal wedding between Prince William and Kate Middleton, appealing to the public to help them spot any troublemakers. [Photo/Agencies]

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