Mark Lusby, Project Co-ordinator for the City Walls Heritage Project, had complained that a Derry City Council-commissioned lighting scheme had resulted in five slots being cut into the City Walls at East Wall, facing the Millennium Forum.
He said the section comprised Seventeenth century features, some of which had been highlighted in the City Walls Gazetteer, launched in 2011 by Environment Minister, Alex Attwood.
But Mr Lusby has now welcomed the intervention of the Minister, who has now called a halt to work on that section of the walls.
The Holywell Trust had brought the issue to the attention of DOE and Council at the weekend and lobbied to have ongoing work on Monday suspended.
Speaking after the Minister’s intervention, Mr Lusby said: “The overall Lighting Scheme is a good initiative which will increase public safety and access to the City Walls.
“We have thanked the DOE Minister for his personal interest in the heritage of the City Walls. We also asked him to ensure that his officials involved heritage organisations, like the Holywell Trust and the Foyle Civic Trust, in any discussions about the remedial work required.”
The Trust also thanked local media for helping to bring the issue to public notice.
“Is important that everyone involved in future schemes for the City Walls, from designers to contractors, have awareness training on the heritage value of the Walls. Everyone working on the City Walls needs to be a guardian of the historic fabric of the Monument,” suggested Mark.
Earlier Mr Lusby had told the Sentinel: “I discovered the damage on Saturday and immediately reported it to Council officials, DOE officials and the NI Historic Monuments Council.
“The Holywell Trust had been planning to involve the community in surveying this section of the City Walls, and recording the gun loops, as part of the Walls 400 History Conference, scheduled for the weekend April 6 and 7.
“We did not expect to have to deal with 21st century lighting fittings inserted into a relatively intact section of 17th Century Walls.”
A spokesperson for Derry City Council said the local authority was working closely with the Northern Ireland Environment Agency (NIEA) with regard to the matter.
Mr Lusby said the section of the City Walls affected contained a series of embrasures, or gun loops.
He said that whilst these had been filled in at some stage, they are still clearly visible, marked out by sandstone blocks at either side of each embrasure.
He added: “Historic fabric once lost, cannot be replaced. Even small changes, however well-intentioned, can accumulate and ultimately result in the loss of original significance.
“It is particularly sad to see features which were clearly identified as significant in the Gazetteer, being compromised visually and physically.
“It is vital that anyone planning or carrying out works on the City Walls receives awareness training on the heritage value of the ancient monument. The Holywell Trust would be happy to assist in providing this training.”
The local heritage officer pointed out the Walls are a scheduled ancient monument in the full guardianship of the DOE.
The policies for the care and management of the City Walls are set out in the City Walls Conservation Plan, launched by the former DOE Minister, Arlene Foster.
Policy 40 states that: “A lighting strategy should be devised which will involve minimal physical impact on the Monument while providing levels of illumination throughout the walkways which will engender a sense of safety.”
The authors of the Conservation Plan further suggested that “the existing fittings should be removed and, as a general rule, new light fittings should be installed at a distance from the Monument either mounted on buildings or in appropriately-designed ground locations.”