Not a common plant in cultivation in the northern hemisphere and often mislabelled when it is. This specimen was in the Botanic garden in Auckland.
Its an accepted New Zealand species on the plant list 
Olearia rani (A.Cunn.) Druce
But not listed as available in the RHS plant finder.
I have some seed sown and fingers crossed it will germinate.

It's taken a while to finally complete after being on the waiting list for a few years, but now with improved editing techniques the result is  probably much better than it would have been.
 New Caledonia is a real hotspot for plant diversity and in particular for its conifers, 43 species all of which occur nowhere else.
Many of the plants featured on the page are not named I am hoping with further research/help to rectify this, please feel free to contact me if you can help.

An article by Charles Quest-Ritson on La Mortola the Italian Villa once owned by Sir Thomas Hanbury (who donated Wisley to the RHS in 1903) is in the RHS Garden magazine February issue.