This search has gone around the world and ended with a family connection only 300km from where I live.
The first thing I noticed in the nominal roll entry of VX50020 Alexander Percy Mason was that he was born in Peru. A little unusual for a 2nd AIF soldier. The next piece of information that was of interest was that Alexander was a POW. Given his date of death was May 1945 I thought it highly possible that he died while in captivity. The Commonwealth War Graves Commission confirmed this but threw up another surprise; Alexander is buried in the Yokohama War Cemetery. This link shows a picture of his cemetery plaque. Alexander was originally a member of Gull Force and was captured on Ambon.
From all this a I was able to determinate the names of his parents but in 1942 they were living at the Crest Hotel in Crowborough, Sussex, England. A probate notice I located for Alexander gave no further information that I could use. The clue that opened up the next line of research was a passenger list from 1920s which showed the Mason family travelling from Lima, Peru to England. From this list I got the names of Alexander's siblings. The first brother I looked at was Harry Russell Mason. On a hunch I looked at the WWII nominal roll again and found this entry. Further research showed that Harry married Annette and was a farmer in Victoria. The thread then ran out in the late 1940s.
For what I could work out Alexander and Harry moved to Australia in the early 1930s, however, two other brothers and a sister remained in England. The first I looked at was Alexander's sister Mary. An internet search of her full name threw up a result of her marriage to Charles Arthur Crofton-Atkins. The entry reads:
Charles Arthur Crofton-Atkins, O.B.E. (1963), of Av. Angamos 1585, Miraqores, Lima, Peru, Director and general Manager of Central Railway of Peru; born 18 January 1906, educated at Rossall; married 3 March 1933 to Mary Phyllis Mason, daughter of Harry Mason of Northwood, Middlesex and Lima Peru.
The web page that gave me this information shows that the Crofton-Atkin's family has a long and distinguished military history. From this entry I could determine the names of Alexander's nephews and I was then able to locate their contact details in the USA and the UK.
And that is where the search came back to Australia. My inquiry to Mary's sons was forwarded to Harry's son, Richard, who I wasn't able to locate in the Australian records. Richard has recently been in contact with me and as it turns out he lives on the north side of Sydney, about 300 km north from where I live.
So this search has taken me from South America to England, Victoria, Ambon, Japan, North America and finally back to New South Wales.
Alexander's medals are in as issued condition and were sent to me by the NSW RSL. The group consists of the 1939-45 Star, the Pacific Star, The War Medal, the Defence medal and the Australian Service Medal 1939-45. The returned medal tally is now 1173.