Tunnels at a former top secret World War Two chemical weapons site in Flintshire are being formally opened to the public on Saturday.

Rhydymwyn Valley History Society has been trying for years to get public access to the tunnels, near Mold, that once housed mustard gas.

The UK government, as the site owner, carried out work to allow the tunnels to open this weekend.

During the 1940s the government made this black-and-white film highlighting the work at Rhydymwyn Valley Works with comments from the then Prime Minister Winston Churchill.

The tunnels housed 48 storage tanks, each containing up to 65 tonnes of mustard gas.

They will now be opened annually for guided tours.