Kevin yes a Tri-Carb when built they were made for around a year in the 1961 -62 period - car originally LHD as shown by chassis number " BT7L ....
Car owner is a member of the Austin Healey club, spoke to him briefly. He had the cars details on the board shown above lying in the grille.
Close up of the board -
Good to read that the Waipu show was big,probably between a 100 and 200 cars at Pahoia.
The poster for the show