Did he also edit Natural Bodybuilder in the early 80's? 
This from a listing online, which also says that there is an article in Bob Kennedy's Muscle Mag International, January 1984, entitled "George Greenwood Remembered"
I managed to find a contact who had that magazine.
The penultimate para apparently says:
'GEORGE GREENWOOD died suddenly on Saturday 9th July 1983 of a seizure. A tragic loss to his family and friends, leaving behind a loving wife, son Tony and daughter Hilary.' There was no mention of any other forename than George.
It's strange that the death isn't on FreeBMD as it before the cutoff date for deaths on that Site.
Does this exact date of death help in finding out what his second forename was without resorting to his birth certificate?