[ireland]

hi all i joined this forum to ask a couple of questions from you knowledgeable folk, i have no experience in watches whatsoever so if i say anything stupid ill apologize in advance, i came across a watch recently that is stamped w&d its 925 silver and appears very old, its not in very good condition now ive seen from several posts that there should be a letter to tell me what year it was made does anyone know what letters respond to what years or indeed anymore info that might help me? i will post pictures if required, tks