It is one of Britain's most prized coral reefs, sitting off the coast of the Cayman Islands which were praised by Prince Charles as a "shining example" of a Commonwealth nation protecting its marine life.

But 15 acres of the coral reef, which is home to critically endangered turtles, could be destroyed to make way for two cruise ship docks as part of plans to boost tourism.

Environmental campaigners warn the George Town Harbour project will see 22 acres of the seabed dredged, and silt sedimentation will turn the “crystal-clear aquamarine waters to murky white”.

In December, the first publicly initiated referendum on the islands will decide the reef's future, after 25 per cent of the electorate signed a petition to take the decision to a vote.

There are fears it may not save the reef as campaigners claim the Government has withheld the latest designs for the docks, and the date of the vote coming so close to Christmas will mean many residents are on holiday.