AN investigation has begun after an important part of a historically significant mill site was destroyed.

Low Mill – off Gresley Road in Keighley – dates back to 1779, was the first cotton mill to be built in Yorkshire and is one of just two Grade II* listed buildings in the town.

The mill was powered by water diverted from the River Worth through a series of sluices into a goit.

But the building has been derelict for decades, and last year it was added to the Save Britain’s Heritage ‘At Risk’ register of historic and heritage buildings that face an uncertain future.

Bradford Council has revealed that it has started an investigation after the historic water features on the site were recently concreted over.

Details of the investigation were discussed at the latest meeting of the council’s district planning panel. Members were debating a planning application to build a steel fabricating workshop in front of the site.

The application had been submitted by JCL Machinery Limited, which had bought a section of the site after the damage was done, unaware of the previous unauthorised work.

Part of the development site included in the plans is the former water feature area.

The application had said the workshop had been designed to “echo the style of the mill” and would not harm the setting of the existing building.

A heritage statement included in the application, written by Craft Design and Build, acknowledged the concerns about the unauthorised works, saying: “Had we have been consulted sooner we would have advised the client not to obtain the site.”

Historic England had said of the application: “The mill is highly significant for a number of reasons including the early date of construction, the fact that it was a cotton mill and the association with Sir Richard Arkwright.

“The application site is to the west of Low Mill and lies over the former waterways and sluices that fed the 18th-century internal waterwheel. These constituted an important curtilage component of the listing but appear to have been destroyed. The destruction constitutes an act of heritage crime.”

The West Yorkshire Archaeological Advisory Service said the mill was “of national and arguably international significance in the development of the region’s textile industry”.

A report to the committee had suggested that the application be refused due to the impact on the listed mill, and the fact that it could prejudice the future development of the site. It added: “The investigation into the destruction of the former waterways and sluices that fed the internal waterwheel of the mill is ongoing.”

Members voted to defer a decision on the workshop application until the investigation had progressed.