Jenners are probing claims a lump of render, thought to be several inches thick, tumbled off the side of the historic department store and crashed on to the pavement, reportedly only narrowly missing those walking past.
The premixed sand and cement mixture is often used to coat the outside of buildings to protect them against the elements.
Fire and rescue crews rushed to the scene to ensure the building was secure following the near miss.
The incident was reported to council building chiefs, however the Evening News understands the retailer - now owned by Mike Ashley's Sport Direct - has launched their own internal probe.
Jenners has been contacted for comment.
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