Wood framed upholstered chair (Moortown LS17)

This is a very sturdy and heavy chair. It has a metal mechanism under the chair that may have been some sort of seat raising device but I think some of it may be missing and I have now idea how it should work. The chair does have a fire label. There are signs of wear on the arms. From a smoke and pet free home. Collection from close to the Harrogate Road end of Gledhow Valley Road please.