1961 the " 50 " understand that at first it was 50 laps - then 50 miles as the track got longer,
Graham Woods archives
Name: Motor Racing Renwick #11 1961 Entry List Renwick 50 Graham Woods .jpg Views: 1524 Size: 101.6 KB

1962 the " 50 " with lap chart.
John Manhire archives from " South Island Motorsport " Facebook page .
Name: Motor Racing Renwick #9 1962 Renwick 50 lap chart John Manhire.jpg Views: 1293 Size: 136.9 KB

1963 a selection of the races.
Sports Cars and Specials -
Name: Motor Racing Renwick #1 1963 Race 2 Sports and Specials Graham Woods.jpg Views: 866 Size: 100.0 KB

Saloons
Name: Motor Racing Renwick #23 1963 Race 3 Allcomer saloon first race Graham Woods.jpg Views: 1179 Size: 90.7 KB

Saloons again - later Race; Handicap
Name: Motor Racing Renwick #15 1963 Race 7 Allcomer saloon handicap Graham Woods.jpg Views: 1268 Size: 98.8 KB

All three from Graham Woods archives.

To follow some from 1966 and the Custaxie as mentioned in the comments