Derbyshire Special Constable police reserve badge

A scarce original circa First World War period 'Derbyshire Special Constable lapel badge'; large gilt circular disc with blue enamel title surround, the centre bearing Crowned Tudor rose on white enamel ground; the reverse impressed with maker's details 'J.R.Gaunt & Son London'. Very good condition, complete with original buttonhole fitting, no stress marks or damage to the enamel, a few very minor nicks to rim, gilt finish remains bright. Diameter 32mm.