G'day Wanda,
The Brush Box is Tristania Conferta with the usual
'variegata' as the varietal name for the variegated form. My spelling may
not be exact and there may have been a name change, but nurseries will know
it. I think you will find that it grows considerably higher than 5m if it is
happy. It's a rainforest tree on the east coast and likes to go up into the
canopy when crowded. When planted in the open it forms a large spreading
dome. Councils make a habit of planting them under power lines so that they
have to butcher them every few years. The variegated form is a beautiful
tree but it has a tendency to throw out a green shoot occasionally which
then proceeds to outgrow the variegated branches, destroying the effect
unless removed, which can be hard when it is high in the tree.

China
Wingham
NSW