Williamson's time of 48.09 minutes was only a couple of minutes behind the record set in 1988 (45.54 minutes). He finished ahead of Lance Downie (51:23) and third-placed Chris Morrissey (53:48).
Developing athlete Hayden Wilde finished fourth (and first junior) in front of defending king Sjors Corporaal. The surprise package was Ben Miller, 47 seconds behind Corporaal.
The Queen of the Mountain title on Saturday went to Ruby Muir, arguably one of Australasia's finest trail runners.
Muir led the women's race from the front and posted a summit time of 42.18 minutes, with previous Kawerau Queen Kim Beckinsale (Pomona Queen) just 37 seconds behind her.
Muir crossed the line to capture her first-ever Kawerau Queen title in 1hr 0min 20sec, a worthy victory but narrowly outside the elusive Sub-60 club on what was a very hot day in Kawerau.
Second place went to Beckinsale (1:03:14) followed by Leslie Saunders in third place (1:11:12).
Nine men made the Sub-60 club in 2014, which included another incredible performance from the super veteran Colin Earwaker (58:52), who earns himself a trip to Pomona along with Williamson, Wilde and Muir, who will all carry the Kiwi flag at the 30th Trans-Tasman International Mountain Race Challenge in Pomona in July 2015.
The organisers would like to acknowledge all the volunteers, marshals and safety services who helped in making this event a success.
Other races held on the day included the Radio 1XX School Relays event and the Prince and Princess race. About 400 athletes took part in the event during a beautiful day in Kawerau.
Kawerau King of the Mountain results
King: 1 Shay Williamson, 2 Lance Downie, 3 Chris Morrissey.
Queen: 1 Ruby Muir, 2 Kim Beckinsale, 3 Leslie Saunders.
Prince: 1 Regan Wilson, 2 Oliver Budd, 3 Kevin Paulsen.
Princess: 1 Evelyn Barton, 2 Tegan Fookes, 3 Jana Longney.
School relay champions: Kawerau South School.
