This is a great vintage "BURGESS MINERALS" Advertising Bottle Opener from the 1920's.  Burgess Minerals were probably the biggest Mineral Water and Ginger Beer Makers in Luton Bedfordshire and were active between 1851-1973.   The opener is stamped "BURGESS" on one side and "MINERALS" On the reverse Side.  It is also stamped Registered Design Numbers.  It does a amazing job of opening bottle caps and is a pleasure to use.  The Opener is made from Cast Iron and the finish has built up a patina of age and wear over decades of use.