WW1 Underground Railway War Service low issue number badge D 297

A rare original First World War circa 1914 period 'Underground Railway war service gilt and enamel lapel badge', blue enamel title surround, Crowned 'Railway Service' to the centre on white enamel ground, the reverse with embossed maker's details 'J.A.Wylie & Co London' and impressed with low official issue number 'D 297'. Good condition, complete with original buttonhole fitting, enamel flaw to central white enamel ground, minor service wear.Diameter approx 27mm.