If you had leaf and habit photos it could at least be possible to tell what species it was. (Of course, some cultivars are hybrids instead). Which would narrow down where to search in references for the specific cultivar. Otherwise camellias are one of those hobbyist hybridizer favorites where there are numbers of named forms that have been circulated. As well as ones that have not been in general commerce. Or even in commerce at all. So that the setting where you encountered this particular plant could be relevant. For instance I've asked occupants of properties housing varieties of other kinds of flowering trees and shrubs such as magnolias and plums if they happened to know the specific kind. And been told more than once that the planting originated as seedlings grown from gathered seeds. So likewise a random camellia not in an arboretum, botanical garden or other dedicated collection could be an unnamed seedling. All the more so if growing on a property where a camellia hobbyist was growing camellias from seed and planting them out in the past.

as ron suggests, it could be a seedling or chance hybrid and not much else to go on. if you google "anemone flowered pink camellia", some images of registered cultivars will come up that appear similar but a bit more elegant. your photo shows one which might very well be a chance seedling as it does not appear (imho) to possess qualities which would qualify it to be listed as a registered cultivar. don't get me wrong as i think it is pretty. one of my favorites is a very simple solid red-flowered seedling that i grew from a seedpod from my neighbors shrub. its simplicity of form and color are what i like about it. it has just 5 or 6 long red petals and looks quite like a tube of lipstick when tight in bud and upon opening looking more tulip-like.

If it was blooming in July (winter over there), you may be able to rule out sasanquas. Seems to have very few petals, about 6 I counted.

Try asking the NZ Camellia Society: www.nzcamelliasociety.co.nz They are local and could drive to the place where you saw it and ask questions (if they are willing in this Covid World, of course).

Such timing would not actually rule out a Sasanqua camellia. Sasanqua in the collective sense used in commercial horticulture where cultivars of x hiemalis, sasanqua and x vernalis are all called Sasanqua camellias.