The Oamaru-based trainer had 10 of the 33 runners at yesterday's trials and collected the spoils in three of the races.
The last heat of the day featured three of Williamson's highest-graded trotters, and Miss Pegasus prevailed after enjoying a run in the trail behind Yankee One.
Springbank Sam finished strongly for second, just a head behind Miss Pegasus.
Williamson said everything was on target for a trip to Addington for Springbank Sam and stable mate Jag's Invasion.
The pair will line up in the $80,000 New Zealand Trotting Championships at group 1 level, before Williamson considers a trip further north with Springbank Sam.
''We've got to have a crack at it.
''He'll head north as well [to the Alexandra Park features in late April and May] as long as he goes half-decent.''
Miss Pegasus and Yankee One are also heading to Canterbury in the next three weeks.
''Yankee One's going to race in a 2000m race at Rangiora or Addington. We're still deciding which way we're going there with him,'' Williamson said.
Alexandra Leaving, the winner of the ninth heat, will start off her campaign again in the next two weeks, as will Dwindle Mist.
Williamson has dubbed Bet's Sun as a ''trials specialist'' as he once again produced a good performance away from an official race day with a big win over stablemate Springbank Eden, who made a mistake during the 2200m heat.
''He's a trials specialist - he wins every trial he ever had - and we'll go wherever we can with him,'' he said.
''He's got the ability to win a maiden for sure, but it's all around his manners.''
Springbank Eden is one of 10 2yr-old trotters nominated for a juvenile race at Rangiora on Sunday.
''He'll go there if they get off the ground with it.''
The Steve Ashton stablemates Sunnivue Bay Boy and Better To Be Bad were given a stern workout in a 1200m mobile pace, in preparation for the sprint series at Forbury Park on April 10.
Sunnivue Bay Boy will be Ashton's representative in that series, while Better To Be Bad will head to Addington the next night for a $15,000 c5 amd greater handicap pace.
The only heat to produce qualifiers was the fourth heat, as the Bill Keeler -trained Al Raza punched clear of Torpedo to win her trial in 2.51.3.
Keeler, who trains at Roxburgh, will give the daughter of Gotta Go Cullect another trial before he thinks about lining her up.
''She needs a bit more practice,'' Keeler said.
Runner-up Torpedo and stablemate Imperial Ace also qualified, pleasing co-trainer Geoff Knight.
He will give both pacers another trial, and will look for a start for Torpedo in Southland at the end of the month.
Tagatease was ''much better'' winning his c0 and faster mobile pace in a good time of 2.47.3, trainer Graeme Anderson said.
A start at Forbury Park next week over 2200m was the preferred option for the Bettor's Delight 4yr-old.
