Haute-Loire's puy lentils have an unexpected ambassador - none other than the third in line to the British throne, Prince George.

Demand for the lentils, which have had EU Protected Designation of Origin status for a decade, exploded in the UK when it was revealed they were a regular on the menu at the €20,000-a-year private school that the Prince attends.

"We have had a lot of requests from customers in Britain since the Daily Mail article, especially from restaurateurs," Antoine Wassner, the head of dried vegetable specialists Sabarot, told AFP.

In the European Union, the term puy lentils may only be used to designate lentils that come from Le Puy, notably the commune of Le Puy-en-Velay, in the Auvergne region, where they have been grown for more than 2,000 years.

The blue-green lentils are considered by many to be the best in the world and are sometimes known as 'poor man's caviar'.