Cheese matured in a cave 500 feet deep in a north Wales mountainside is to be revealed as a wonder of the world to a Japanese TV audience of 10 million people.

A crew for Japanese TV network TBS followed the story of how Dragon cheese’s unique Slate Cavern Aged Cheddar made by South Caernarfon Creameries gets its unique flavour, by being matured in the Llechwedd slate cavern at Blaenau Ffestiniog.

It will feature in a special episode of the programme Discovery of the World’s Wonders (Sekai Fushigi Hakken), to be aired during the Welsh Rugby World Cup which is being held for the first time in Japan.

Presenter Mariko Miyachi was not told what was stored in the former slate mine which operated from 1846 to 1972, and has 250 chambers in 25 miles of tunnels on 16 levels.

Once 500 feet deep she is taken into a chamber where hundreds of wooden boxes are stacked, and shouts in surprise when the contents are revealed by Linda Lewis Williams, South Caernarfon Creameries’ head of new product development.

“Wow! Cheese!”, she exclaimed to the camera, after asking what is in the boxes adding: “This is the last thing I expected to see down a slate mine!

“I wasn’t told what to expect so it was a really exciting surprise to find the cheese down there.

“It’s fascinating to learn about the history of the mines and how the cheese is made this way.”

See this week’s north editions for the full story, in shops and online on Thursday