Engineers repairing a broken gas main have unearthed a hidden part of Riddlesden’s history.

Northern Gas Networks was working on an emergency repair to pipework in Dunkirk Rise when its excavation equipment opened up a bigger-than-expected hole.

The chasm turned out to be a mineshaft from a colliery that operated on the site from the mid-1700s until its closure in the 1920s.

Dean Woolley, who was managing the excavation, said: “It’s not every day you dig a hole that suddenly ends up about 400 feet deep!

“We’ve worked in co-operation with both Bradford Council and the National Coal Board to ensure the situation is handled safely and correctly, considering the heritage and historical importance of the pit shaft.

“We have fitted high fencing to cordon off the metre-long hole and placed metal plates over it to ensure the safety of the local residents, many of whom were unaware of their historical coal mining connection.

“This discovery seems to have really surprised everyone, and many local people were unaware the area ever had a working coal mine.”

Northern Gas Networks has now replaced the old metal pipes in the vicinity of the pit shaft with modern, more resilient plastic piping, and renewed the pipework leading to customers’ homes.

A National Coal Board representative will visit the site to decide on the best way to reinstate the pit shaft.