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So prized were these 'horns' that Elizabeth I paid £10,000 for one, equivalent to the cost of an entire castle.

Narwhal tusks can grow to over 10ft (3m) and weigh up to 22lbs. However, at 7ft 8in (2.34m), the antique example seen at Clarke Gammon Wellers (17.5% buyer's premium) of Loseley Park, Guildford on July 4 was as good as one might expect to find.

In excellent condition, (the tips are often broken but here it was intact), it had been consigned by a vendor who believed his grandparents had bought it while living in India in the 1920s. Offered complete with relevant CITES documentation, it proved the subject of lively competition between a dealer and a local collector who ultimately bought it at £10,500.        

Incidentally, it was recently reported that scientists in the United States have discovered the secret of the narwhal tusk.

More than 10 million tiny nerve connections give the tooth an extremely sensitive surface capable of detecting changes in water temperature, pressure and particle gradients.