I found three individual S Offord's showing up in the medal rolls, but cross-checking showed that none of them were a Simeon, although all three of them were clearly pre-war soldiers. Is it possible he was serving with the forces of another country? A quick check of the WW1 service records for Australia, Canada, and New Zealand doesn't produce a match though, and if he had died while serving with a Commonwealth country he should be listed on the CWGC website. The other possibility is that he served using an alias, which is going to make him virtually impossible to find.