With reference to enquiries regarding both Albert Percy Whiteman and Victor Davey, I believe I may have some helpful information for you both.
From further internet research, I can definit6ely confirm that Albert Percy Whiteman was a member of No 3 British Air Mission to Belgium. He is identified as being aboard the SS Aboukir when it was sunk by S34 and many of the survivors of the torpedoing were subsequently machine gunned where seen in the water using its searchlights. Only some 33 or so were rescued, mainly by the destroyer HMS Codrington some 6 hours later at daybreak.
Naturally there is a deal of confusion as very little of any passenger manifest survives, but the presence of other Army and particularly RASC casualties could support the contention that Victor Davey was also aboard.
The Army used the date of 27th May for Abukir casualties, even though the vessel was lost in the early hours of the 28th May. Bodies were washed ashore in the UK as well as France, Belgian and the Friesian Islands. However, I haven’t yet found anything definitive to him actually being aboard Abukir rather than one of the 220 plus vessels sunk during the Dunkirk evacuation. He could therefore have been on another vessel unless we can discover why he was linked to Abukir.
I believe you both have my email address, so please respond via that if you have anything further.