The Oamaru harness racing trainer has forged his reputation around training trotters. In fact, of the 2769 starters Williamson has taken to the races since he first took out a licence to train in the 1992-93 season, 2566 of those have been trotters.
Harness racing meetings are made up largely of pacing races, so Williamson generally only has one or two cracks at a win at each meeting, making his achievement all the more remarkable.
Williamson's victory with Pyramid Magic at Gore on Sunday took him to the 500-win mark - 481 of those wins coming in trotting races.
Do the maths on the figures above and it means Williamson has trained 19 pacing winners from 203 starters over the years. But, bar one appearance from the galloping pacemaker Ask Yourself at Oamaru last season, a set of hopples at the Williamson Racing Stables establishment is about as rare as John Key and Kim Dotcom sitting down for a cup of tea and a chinwag.
So it stands to reason that Williamson is more focused on the 500 trotting winners, which he hopes to rack up sometime this season.
''It's a milestone that we're pleased to do it. We've still got 19 to go [for the trotting mark],'' he said.
''But hey, it's still a milestone, and something that the whole team are pretty happy with. Everyone's played a part in achieving it.''
After stints working for horsemen like Dick Prendergast, Williamson first mixed the horses in with working at a tannery, but only became a public trainer for Harness Racing New Zealand licensing purposes from the 2006-07 season.
''I haven't had a professional licence all that long, but we've been able to rack up a few wins with a few good horses.''
Williamson's training operation is largely a family affair. He is joined by wife Bev, sons Matthew and Brad and Matthew's girlfriend, Charlotte Purvis, while Steve Allen is also a valued member of staff.
Apart from the robust debates that go on throughout the day between Williamson and his two sons (eldest brother Nathan trains in Southland), Williamson is glad to have them around.
''That's the big thing,'' he said.
''When they were wee, we were dragging them around, and little did we know that they would become so successful in their own right. With a wee bit of help from their mother and father, they've been able to successfully get a start, anyway - it's over to them from here. But it is a pretty tough game to get ahead.''
So the 19 wins are the main focus for the season, as Williamson expects the season overall to be a bit quieter than last year's 58-win tally with many horses getting ''near their mark''.
''That's the problem. There are only so many wins in any horse. If they win and have a big season one season, you're probably looking at having a lesser season the next.
''We'll definitely be well back this season, but in saying that, we might be quite strong again the next year. We broke in some quite promising yearlings that will be 3yr-olds next [season] and some of them look quite good. Whether they're good enough to race as 2yr-olds will remain to be seen.''
