He is the only RAF aircrew who served with 75 Squadron who is alive and a New Zealand resident.
He recalls the night he "fell out" of a burning plane over Germany and, drifting earthwards in his parachute, wondered why other white canopies were not sharing the black and silent sky.
Just minutes before he had crawled to a large hole in the belly of the bomber and fallen through, assuming he was mortally wounded and his crew mates doomed.
Hanging in the soft cool air, he recalls coming out of an oxygen-starved stupor and being horrified at what he had done.
"I felt as a sailor must feel, having fallen overboard and seeing his ship sailing off without him," he recounted yesterday at his home in Grey Lynn, Auckland.
It was 1945 and he was on his 32nd and last scheduled bombing mission over Germany. He fondly holds a framed photograph of the 75 (NZ) Squadron C Flight of the Royal Airforce in 1945 and points to himself with black hair and moustache, aged 19, a sergeant flight engineer.
The young Scot was in the bomber crew with three New Zealanders: John Wood (pilot), Jack Pauling (navigator) and Gerry Newey (wireless operator) and two Canadian gunners.
After a safe landing near the liberating American forces and being returned to England he learned why his crewmates had not parachuted to safety.
The "warm blood" drenching his face came not from a flak wound but from a tank of de-icing fluid that had been hit and holed.
Some crewmates' parachutes were burned so escape was impossible.
They stifled the fire and with only a small piece of charred map to guide them, "got home in a very charred and blackened kit".
Mr Wood received the Distinguished Flying Cross and Mr Pauling the Distinguished Flying Medal.
Mr Williamson, a match-fit masters fencing champion, has lived in New Zealand since 1974.
"I had a beer with Jack Pauling after the war - I think they are all finished now.
"Gerry Newey was a great guy. The last time I saw Gerry was when I shouted to him that we would have to get out through the great hole in the gun turret and I collapsed."
Mr Newey, who died in 1977, had noted in his log book "Lost engineer".
Veterans are due to attend the dedication of the Bomber Command Memorial in London on June 28, and also visit their former bases.
A spokesman for the minister's office said that to be part of the official delegation, veterans had to have served New Zealand in Bomber Command with the Royal New Zealand Air Force and meet medical fitness criteria for travel.
BOMBER CREW
* 6000 New Zealanders volunteered
* 2000 were killed
* 55,573 total bomber crew killed
* $11.5m memorial dedication in London, June 28
* 60 New Zealanders could attend in official party
