The 30-year-old Finch shot an even-par 72 for a three-stroke victory over Australians Steven Bowditch (72) and Paul Sheehan (69) in the event sanctioned by the European and Australasian tours. Finish had a 14-under 274 total on The Hills course.
'Going into today, I felt it was in my hands and if I played well, played as I had been all week, this would be the outcome,' Finch said. 'I stumbled a bit on the back nine when I started thinking too much about what I was doing. It's the first time I've been in this position and it was difficult to know how to do it.'
Charles, the oldest man to make the cut on a major non-seniors tour, added a 70 Sunday to rounds of 75, 68 and 71 to tie for 23rd at 4 under.
The first left-hander to win a major championship when he took the 1963 British Open, Charles won the New Zealand Open as an amateur in 1954 and added the 1966, 1970 and 1973 titles as a pro.