This search was a little complicated because of the soldier taking his step father's name but keeping his own surname as well. Once I had sorted that out it became a bit easier to located details about William Irvine Dyce.
William was 19 when he was killed in action at Gallipoli. Luckily, this bio provided a wealth of information about William's wider family. The bio also contained a photo which I've added below. William's brother didn't survive for many years after WWI due to his own injuries so the immediate family line appeared to end. Using Ancestry.com there was no clues which indicated any family connection for me to chase down.
Knowing that William was from a small island community I took a punt and wrote to the local paper, The Orcadian, to see it I could locate any family members. Shortly after publication of this letter I received an email for the a great niece of William's on his mother's side. The medals will be sent to this family in the near future.
Thanks goes to Max of Geraldton who acted as the intermediary between donor family and me. The medals were originally obtained by another veteran with the sole purpose of returning them to the family. How they turned up in Australia is anyone's guess.
The returned medal tally is now 1407.