Harris of Liverpool Hallmarks

I recently purchased a pocket watch marked Harris of Liverpool. The dust cover & front cover contain five hallmarks/ makers marks, they form an oval in shape and consist of: 1) The letter U (with serif) 2)Leopard/Lion-head without crown 3) King/Queen crown 4)The #18 (without the # symbol) and 5) The stamped initials JM any information you can provide is greatly appreciated.