Harness Racing New Zealand has accorded Williamson the accolade, crediting him with a total of 266 wins.
Williamson has won 27 races for trotters this season.
Maori Invasion has won at Gore and Invercargill from seven starts in his first season of racing. He was disqualified from second at Ashburton at his last start.
Lyalldale Invasion, the winner of four races, has been placed in five of his eight starts this season. He finished second to Unique Star at Addington at his last start. He won at Addington 12 months ago.
The 3.21.1 for 2600m by Mo Hahn at Rangiora on Sunday has been recognised as a New Zealand record for a 3yr-old trotter.
This was confirmed by Andrew Morris, information manager for HRNZ.
He said the timing had met the official requirements.
Mo Hahn bettered the 3.22.4 set by the filly Gina's Best at Addington in July 2004.
It was the third win for Mo Hahn in nine starts. He won as a 2yr-old at Waterlea in June last year. He is trained there by Dean Hunter, who races the Earl-Avon Develd gelding with his brother-in-law, Allan Hahn, of Nelson.
Hunter won five races with Avon Develd, who won first up as a 2yr-old at Addington in 1998. The daughter of Gee Whiz and Global Dancer died in 2008, a month after Mo Hahn was weaned. Earl De Veld, one of her two other foals, won for Hunter at Wanganui in 2006.
Scott Phelan, the Papakura horseman, is to take up a position as stable foreman for the Mark Purdon stable in Australia.
Phelan (29) will begin his employment in October at the new Purdon stable close to Melton in Victoria.
Phelan has worked for Mark Purdon's elder brother, Barry, for 14 years, the last seven in a training partnership. The pair have produced 122 winners for stakes of $2 million.
The Mark Purdon and Grant Payne stable would still operate their Rolleston stable but their Pukekohe barn was likely to close.
The Melton stable will have a staff of three with 25-30 horses in work, many of whom Phelan will drive on raceday.
