Brass 22mm diameter, weight 5.56gm.  WM GRIFFIN  27 LOMBARD ST LONDON  PUBLISHER OF THE NATIONAL, SOCIETY, AND OTHER MEDALS around head lof Brunel left within circle, SIR I. M.   BRUNEL at sides.  Rv. Double tunnel entrance, in ex. THAMES TUNNEL COMMENCED 1824  OPENED 1842.    Withers TB3, 3030.  Lightly toned, with some original colour and lustre, EF