The Hepburn family (Grafton, then Lismore, personal communications, 2000) state that trial exports of high grade camphor laurel logs and sawn timber were greatest around c1946-47, especially with fast grown trees from the Dorroughby area, north of Lismore. This was one of a handful of early settled locales that has deep soil, some altitude, southern facing slopes not prone to drought and favoured by higher than average rainfall, as compared to most surrounding lower altitude districts.
However, favourable export prices received at that time from Japan did not continue much past 1940, and, increasingly, camphor logs were severely tarnished by 'embedding' of fencing wire, barbed wire and bottles(!) This was due to the rapid cambium growth and expansion of camphor trunks at and around 'DBH' or shoulder height.
Between 1946 and 1948 up to 30 large camphor stumps per month were sent by boat for milling in Sydney, with trunk stumps averaging around 2 to 3 metres long and diameter ie >5m3 per tree. These would have been from the earliest known plantings, after 1885 in the Dorroughby and surrounding areas, ie trees up to 65 years old, but almost certainly as little as 50 years of age.