Here is some information and a couple of websites to look at.
PLAXTON, Sergeant Mairne Edwin (650538) - Distinguished Flying Medal - No.178 Squadron - awarded as per London Gazette dated 17 August 1943. Born in Victoria, 1914; home in British Columbia; former market gardener. Enlisted 1937; killed in action 11 February 1944 over Yugoslavia. DHist file 181.005 D.270 does not list him, but DHist file 181.005 D.271 does; as of late 1940 he was an Aircraft Hand (Flight Mechanic) with No.1 Wing, Hednesford. Air Ministry Bulletin 11132 refers.
...night in June 1943, Flight Engineer of aircraft attacking airfield at Comiso. Aircraft hit by flak, two of crew injured, fire near entrance hatch. Plaxton quelled flames, rendered efficient first aid to wounded comrades; also freed rear gunner who was trapped in turret. By his initiative and promptitude contributed materially to safe return.
NOTE: Ian Tavender records his recommendation, found in Public Record Office Air 2/4995, in his book The Distinguished Flying Medal Register for the Second World War (London, Savannah Publications, 2000). Name give as Nairne Edward Plaxton.
Sergeant Plaxton, on the night of 22nd/23rd June 1943, was detailed to fly as Flight Engineer to Sergeant Tattersall in Halifax BB357 "J", scheduled to attack Comiso aerodrome. The aircraft was hit and severely damaged by anti-aircraft fire over the target, a fire breaking out near the oxygen storage forward of the entrance hatch and two crew members were injured. Sergeant Plaxton, having first turned off the oxygen supply, went back and extinguished the fire. He then went forward again and attended to the wounded men, applying a tourniquet to 1116779 Sergeant J. Houston and making the other man as comfortable as possible. As contact had been lost with the rear gunner, Sergeant Plaxton went aft to investigate and found the doors of the turret had been damaged and were jammed. He successfully forced open the doors and helped the rear gunner out. The presence of mind and coolness, together with courage under exceptionally trying circumstances, which Sergeant Plaxton displayed was undoubtedly largely responsible for enabling his captain to pilot the aircraft to a safe landing.
Keep an eye out for a book entitled:- RAF Bomber Losses - Middle East & Mediterranean; vol 2. by D. Gunby (Author), P. Temple (Author)
But I don't think that it has been published yet.