I've successfully used Tararau buttermilk to make a starter. Picked up a 600 ml carton, warmed it in the hot water cupboard for 6 hours (which was a bit long; I would try 4 hours, or just leave at room temp next time). Ended up with a yogurt like culture, which gave me around 28 or 30 ice cubes. Used 2 today to make a Lancashire and the make all proceeded normally, and I got a good curd. So, for anyone in NZ looking for an easy source of mesophillic culture, that one works.
P.S. I've e-mailed Tararau to see if they would tell me what cultures they use, but it's commericially sensitive information. Oh well, it seems to make a decent cheese.