It's a business bonanza no-one could have predicted. Shopkeepers in a north Kent town say their trade has been boosted by the arrival of a beluga whale in the Thames estuary. The whale - nicknamed 'Benny' - was first spotted two months ago and has since become a real draw for tourists. And some traders are now cashing in on Benny's fame. Abigail Bracken sent this report from Gravesend.