Names on War Memorials across the country may not be accurate as Guy has said, I know of 2 in my home town that were added, 1 after 100 years and that was because family were no longer in the area when the War Memorial was built. Next question is have you tried the CWGC for the 1918 one? Those that died after WWI of their injuries (my grandmother's brother did) are still listed as a casualty and have a CWGC gravestone in the local cemetery of his birth. With regards to 1952, this could be a problem as the CWGC's priority is the maintenance of the records for both World Wars BUT, as in the case of Aden, they do manage the two cemeteries out there on behalf of the MOD, so it is possible that they may be doing the same for Egypt. However, they are so inundated with queries, it can take several weeks before you get a reply.
Hope this helps and good luck.
Brian